diff --git a/backend/pom.xml b/backend/pom.xml
index 97d8c7f65..a0f1c9b7e 100644
--- a/backend/pom.xml
+++ b/backend/pom.xml
@@ -132,6 +132,19 @@
       <artifactId>springdoc-openapi-starter-webmvc-api</artifactId>
       <version>2.2.0</version>
     </dependency>
+    <!-- 高阶 Java 客户端 -->
+    <dependency>
+      <groupId>org.opensearch.client</groupId>
+      <artifactId>opensearch-java</artifactId>
+      <version>3.2.0</version>
+    </dependency>
+
+    <!-- 低阶 RestClient，提供 org.opensearch.client.RestClient 给你的 RestClientTransport 用 -->
+    <dependency>
+      <groupId>org.opensearch.client</groupId>
+      <artifactId>opensearch-rest-client</artifactId>
+      <version>3.2.0</version>
+    </dependency>
   </dependencies>
 
   <build>
diff --git a/backend/src/main/java/com/openisle/search/NoopSearchIndexer.java b/backend/src/main/java/com/openisle/search/NoopSearchIndexer.java
new file mode 100644
index 000000000..afaca419c
--- /dev/null
+++ b/backend/src/main/java/com/openisle/search/NoopSearchIndexer.java
@@ -0,0 +1,14 @@
+package com.openisle.search;
+
+public class NoopSearchIndexer implements SearchIndexer {
+
+  @Override
+  public void indexDocument(String index, SearchDocument document) {
+    // no-op
+  }
+
+  @Override
+  public void deleteDocument(String index, Long id) {
+    // no-op
+  }
+}
diff --git a/backend/src/main/java/com/openisle/search/OpenSearchConfig.java b/backend/src/main/java/com/openisle/search/OpenSearchConfig.java
new file mode 100644
index 000000000..8ab484059
--- /dev/null
+++ b/backend/src/main/java/com/openisle/search/OpenSearchConfig.java
@@ -0,0 +1,78 @@
+package com.openisle.search;
+
+import org.apache.hc.client5.http.auth.AuthScope;
+import org.apache.hc.client5.http.auth.UsernamePasswordCredentials;
+import org.apache.hc.client5.http.impl.auth.BasicCredentialsProvider;
+import org.apache.hc.core5.http.HttpHost;
+import org.opensearch.client.RestClient;
+import org.opensearch.client.RestClientBuilder;
+import org.opensearch.client.json.jackson.JacksonJsonpMapper;
+import org.opensearch.client.opensearch.OpenSearchClient;
+import org.opensearch.client.transport.rest_client.RestClientTransport;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.util.StringUtils;
+
+@Configuration
+@EnableConfigurationProperties(OpenSearchProperties.class)
+public class OpenSearchConfig {
+
+  @Bean(destroyMethod = "close")
+  @ConditionalOnProperty(prefix = "app.search", name = "enabled", havingValue = "true")
+  public RestClient openSearchRestClient(OpenSearchProperties properties) {
+    RestClientBuilder builder = RestClient.builder(
+      new HttpHost(properties.getScheme(), properties.getHost(), properties.getPort())
+    );
+    if (StringUtils.hasText(properties.getUsername())) {
+      BasicCredentialsProvider credentialsProvider = new BasicCredentialsProvider();
+      credentialsProvider.setCredentials(
+        new AuthScope(properties.getHost(), properties.getPort()),
+        new UsernamePasswordCredentials(
+          properties.getUsername(),
+          properties.getPassword() != null ? properties.getPassword().toCharArray() : new char[0]
+        )
+      );
+      builder.setHttpClientConfigCallback(httpClientBuilder ->
+        httpClientBuilder.setDefaultCredentialsProvider(credentialsProvider)
+      );
+    }
+    return builder.build();
+  }
+
+  @Bean(destroyMethod = "close")
+  @ConditionalOnBean(RestClient.class)
+  public RestClientTransport openSearchTransport(RestClient restClient) {
+    return new RestClientTransport(restClient, new JacksonJsonpMapper());
+  }
+
+  @Bean
+  @ConditionalOnBean(RestClientTransport.class)
+  public OpenSearchClient openSearchClient(RestClientTransport transport) {
+    return new OpenSearchClient(transport);
+  }
+
+  @Bean
+  @ConditionalOnBean(OpenSearchClient.class)
+  public SearchIndexInitializer searchIndexInitializer(
+    OpenSearchClient client,
+    OpenSearchProperties properties
+  ) {
+    return new SearchIndexInitializer(client, properties);
+  }
+
+  @Bean
+  @ConditionalOnBean(OpenSearchClient.class)
+  public SearchIndexer openSearchIndexer(OpenSearchClient client, OpenSearchProperties properties) {
+    return new OpenSearchIndexer(client);
+  }
+
+  @Bean
+  @ConditionalOnMissingBean(SearchIndexer.class)
+  public SearchIndexer noopSearchIndexer() {
+    return new NoopSearchIndexer();
+  }
+}
diff --git a/backend/src/main/java/com/openisle/search/OpenSearchIndexer.java b/backend/src/main/java/com/openisle/search/OpenSearchIndexer.java
new file mode 100644
index 000000000..5bffa0364
--- /dev/null
+++ b/backend/src/main/java/com/openisle/search/OpenSearchIndexer.java
@@ -0,0 +1,51 @@
+package com.openisle.search;
+
+import java.io.IOException;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.opensearch.client.opensearch.OpenSearchClient;
+import org.opensearch.client.opensearch.core.DeleteRequest;
+import org.opensearch.client.opensearch.core.IndexRequest;
+import org.opensearch.client.opensearch.core.IndexResponse;
+
+@Slf4j
+@RequiredArgsConstructor
+public class OpenSearchIndexer implements SearchIndexer {
+
+  private final OpenSearchClient client;
+
+  @Override
+  public void indexDocument(String index, SearchDocument document) {
+    if (document == null || document.entityId() == null) {
+      return;
+    }
+    try {
+      IndexRequest<SearchDocument> request = IndexRequest.of(builder ->
+        builder.index(index).id(document.entityId().toString()).document(document)
+      );
+      IndexResponse response = client.index(request);
+      if (log.isDebugEnabled()) {
+        log.debug(
+          "Indexed document {} into {} with result {}",
+          document.entityId(),
+          index,
+          response.result()
+        );
+      }
+    } catch (IOException e) {
+      log.warn("Failed to index document {} into {}", document.entityId(), index, e);
+    }
+  }
+
+  @Override
+  public void deleteDocument(String index, Long id) {
+    if (id == null) {
+      return;
+    }
+    try {
+      client.delete(DeleteRequest.of(builder -> builder.index(index).id(id.toString())));
+    } catch (IOException e) {
+      log.warn("Failed to delete document {} from {}", id, index, e);
+    }
+  }
+}
diff --git a/backend/src/main/java/com/openisle/search/OpenSearchProperties.java b/backend/src/main/java/com/openisle/search/OpenSearchProperties.java
new file mode 100644
index 000000000..f236abcb5
--- /dev/null
+++ b/backend/src/main/java/com/openisle/search/OpenSearchProperties.java
@@ -0,0 +1,61 @@
+package com.openisle.search;
+
+import lombok.Getter;
+import lombok.Setter;
+import org.springframework.boot.context.properties.ConfigurationProperties;
+
+@Getter
+@Setter
+@ConfigurationProperties(prefix = "app.search")
+public class OpenSearchProperties {
+
+  private boolean enabled = false;
+  private String host = "localhost";
+  private int port = 9200;
+  private String scheme = "http";
+  private String username;
+  private String password;
+  private String indexPrefix = "openisle";
+  private boolean initialize = true;
+  private int highlightFragmentSize = 200;
+
+  private Indices indices = new Indices();
+
+  public String postsIndex() {
+    return indexName(indices.posts);
+  }
+
+  public String commentsIndex() {
+    return indexName(indices.comments);
+  }
+
+  public String usersIndex() {
+    return indexName(indices.users);
+  }
+
+  public String categoriesIndex() {
+    return indexName(indices.categories);
+  }
+
+  public String tagsIndex() {
+    return indexName(indices.tags);
+  }
+
+  private String indexName(String suffix) {
+    if (indexPrefix == null || indexPrefix.isBlank()) {
+      return suffix;
+    }
+    return indexPrefix + "-" + suffix;
+  }
+
+  @Getter
+  @Setter
+  public static class Indices {
+
+    private String posts = "posts";
+    private String comments = "comments";
+    private String users = "users";
+    private String categories = "categories";
+    private String tags = "tags";
+  }
+}
diff --git a/backend/src/main/java/com/openisle/search/SearchDocument.java b/backend/src/main/java/com/openisle/search/SearchDocument.java
new file mode 100644
index 000000000..4dc699f34
--- /dev/null
+++ b/backend/src/main/java/com/openisle/search/SearchDocument.java
@@ -0,0 +1,16 @@
+package com.openisle.search;
+
+import java.time.Instant;
+import java.util.List;
+
+public record SearchDocument(
+  String type,
+  Long entityId,
+  String title,
+  String content,
+  String author,
+  String category,
+  List<String> tags,
+  Long postId,
+  Instant createdAt
+) {}
diff --git a/backend/src/main/java/com/openisle/search/SearchDocumentFactory.java b/backend/src/main/java/com/openisle/search/SearchDocumentFactory.java
new file mode 100644
index 000000000..786a554e0
--- /dev/null
+++ b/backend/src/main/java/com/openisle/search/SearchDocumentFactory.java
@@ -0,0 +1,125 @@
+package com.openisle.search;
+
+import com.openisle.model.Category;
+import com.openisle.model.Comment;
+import com.openisle.model.Post;
+import com.openisle.model.Tag;
+import com.openisle.model.User;
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.util.Collections;
+import java.util.List;
+import java.util.Objects;
+import java.util.stream.Collectors;
+
+public final class SearchDocumentFactory {
+
+  private SearchDocumentFactory() {}
+
+  public static SearchDocument fromPost(Post post) {
+    if (post == null || post.getId() == null) {
+      return null;
+    }
+    List<String> tags = post.getTags() == null
+      ? Collections.emptyList()
+      : post
+        .getTags()
+        .stream()
+        .map(Tag::getName)
+        .filter(Objects::nonNull)
+        .collect(Collectors.toList());
+    return new SearchDocument(
+      "post",
+      post.getId(),
+      post.getTitle(),
+      post.getContent(),
+      post.getAuthor() != null ? post.getAuthor().getUsername() : null,
+      post.getCategory() != null ? post.getCategory().getName() : null,
+      tags,
+      post.getId(),
+      toInstant(post.getCreatedAt())
+    );
+  }
+
+  public static SearchDocument fromComment(Comment comment) {
+    if (comment == null || comment.getId() == null) {
+      return null;
+    }
+    Post post = comment.getPost();
+    List<String> tags = post == null || post.getTags() == null
+      ? Collections.emptyList()
+      : post
+        .getTags()
+        .stream()
+        .map(Tag::getName)
+        .filter(Objects::nonNull)
+        .collect(Collectors.toList());
+    return new SearchDocument(
+      "comment",
+      comment.getId(),
+      post != null ? post.getTitle() : null,
+      comment.getContent(),
+      comment.getAuthor() != null ? comment.getAuthor().getUsername() : null,
+      post != null && post.getCategory() != null ? post.getCategory().getName() : null,
+      tags,
+      post != null ? post.getId() : null,
+      toInstant(comment.getCreatedAt())
+    );
+  }
+
+  public static SearchDocument fromUser(User user) {
+    if (user == null || user.getId() == null) {
+      return null;
+    }
+    return new SearchDocument(
+      "user",
+      user.getId(),
+      user.getUsername(),
+      user.getIntroduction(),
+      null,
+      null,
+      Collections.emptyList(),
+      null,
+      toInstant(user.getCreatedAt())
+    );
+  }
+
+  public static SearchDocument fromCategory(Category category) {
+    if (category == null || category.getId() == null) {
+      return null;
+    }
+    return new SearchDocument(
+      "category",
+      category.getId(),
+      category.getName(),
+      category.getDescription(),
+      null,
+      null,
+      Collections.emptyList(),
+      null,
+      null
+    );
+  }
+
+  public static SearchDocument fromTag(Tag tag) {
+    if (tag == null || tag.getId() == null) {
+      return null;
+    }
+    return new SearchDocument(
+      "tag",
+      tag.getId(),
+      tag.getName(),
+      tag.getDescription(),
+      null,
+      null,
+      Collections.emptyList(),
+      null,
+      toInstant(tag.getCreatedAt())
+    );
+  }
+
+  private static Instant toInstant(LocalDateTime time) {
+    return time == null ? null : time.atZone(ZoneId.systemDefault()).toInstant();
+  }
+}
diff --git a/backend/src/main/java/com/openisle/search/SearchIndexEventListener.java b/backend/src/main/java/com/openisle/search/SearchIndexEventListener.java
new file mode 100644
index 000000000..5565b039e
--- /dev/null
+++ b/backend/src/main/java/com/openisle/search/SearchIndexEventListener.java
@@ -0,0 +1,33 @@
+package com.openisle.search;
+
+import com.openisle.search.event.DeleteDocumentEvent;
+import com.openisle.search.event.IndexDocumentEvent;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Component;
+import org.springframework.transaction.event.TransactionPhase;
+import org.springframework.transaction.event.TransactionalEventListener;
+
+@Slf4j
+@Component
+@RequiredArgsConstructor
+public class SearchIndexEventListener {
+
+  private final SearchIndexer searchIndexer;
+
+  @TransactionalEventListener(phase = TransactionPhase.AFTER_COMMIT, fallbackExecution = true)
+  public void handleIndex(IndexDocumentEvent event) {
+    if (event == null || event.document() == null) {
+      return;
+    }
+    searchIndexer.indexDocument(event.index(), event.document());
+  }
+
+  @TransactionalEventListener(phase = TransactionPhase.AFTER_COMMIT, fallbackExecution = true)
+  public void handleDelete(DeleteDocumentEvent event) {
+    if (event == null) {
+      return;
+    }
+    searchIndexer.deleteDocument(event.index(), event.id());
+  }
+}
diff --git a/backend/src/main/java/com/openisle/search/SearchIndexEventPublisher.java b/backend/src/main/java/com/openisle/search/SearchIndexEventPublisher.java
new file mode 100644
index 000000000..4f5fbbdd6
--- /dev/null
+++ b/backend/src/main/java/com/openisle/search/SearchIndexEventPublisher.java
@@ -0,0 +1,99 @@
+package com.openisle.search;
+
+import com.openisle.model.Category;
+import com.openisle.model.Comment;
+import com.openisle.model.Post;
+import com.openisle.model.PostStatus;
+import com.openisle.model.Tag;
+import com.openisle.model.User;
+import com.openisle.search.event.DeleteDocumentEvent;
+import com.openisle.search.event.IndexDocumentEvent;
+import lombok.RequiredArgsConstructor;
+import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.stereotype.Component;
+
+@Component
+@RequiredArgsConstructor
+public class SearchIndexEventPublisher {
+
+  private final ApplicationEventPublisher publisher;
+  private final OpenSearchProperties properties;
+
+  public void publishPostSaved(Post post) {
+    if (!properties.isEnabled() || post == null || post.getStatus() != PostStatus.PUBLISHED) {
+      return;
+    }
+    SearchDocument document = SearchDocumentFactory.fromPost(post);
+    if (document != null) {
+      publisher.publishEvent(new IndexDocumentEvent(properties.postsIndex(), document));
+    }
+  }
+
+  public void publishPostDeleted(Long postId) {
+    if (!properties.isEnabled() || postId == null) {
+      return;
+    }
+    publisher.publishEvent(new DeleteDocumentEvent(properties.postsIndex(), postId));
+  }
+
+  public void publishCommentSaved(Comment comment) {
+    if (!properties.isEnabled() || comment == null) {
+      return;
+    }
+    SearchDocument document = SearchDocumentFactory.fromComment(comment);
+    if (document != null) {
+      publisher.publishEvent(new IndexDocumentEvent(properties.commentsIndex(), document));
+    }
+  }
+
+  public void publishCommentDeleted(Long commentId) {
+    if (!properties.isEnabled() || commentId == null) {
+      return;
+    }
+    publisher.publishEvent(new DeleteDocumentEvent(properties.commentsIndex(), commentId));
+  }
+
+  public void publishUserSaved(User user) {
+    if (!properties.isEnabled() || user == null) {
+      return;
+    }
+    SearchDocument document = SearchDocumentFactory.fromUser(user);
+    if (document != null) {
+      publisher.publishEvent(new IndexDocumentEvent(properties.usersIndex(), document));
+    }
+  }
+
+  public void publishCategorySaved(Category category) {
+    if (!properties.isEnabled() || category == null) {
+      return;
+    }
+    SearchDocument document = SearchDocumentFactory.fromCategory(category);
+    if (document != null) {
+      publisher.publishEvent(new IndexDocumentEvent(properties.categoriesIndex(), document));
+    }
+  }
+
+  public void publishCategoryDeleted(Long categoryId) {
+    if (!properties.isEnabled() || categoryId == null) {
+      return;
+    }
+    publisher.publishEvent(new DeleteDocumentEvent(properties.categoriesIndex(), categoryId));
+  }
+
+  public void publishTagSaved(Tag tag) {
+    if (!properties.isEnabled() || tag == null || !tag.isApproved()) {
+      return;
+    }
+    SearchDocument document = SearchDocumentFactory.fromTag(tag);
+    if (document != null) {
+      publisher.publishEvent(new IndexDocumentEvent(properties.tagsIndex(), document));
+    }
+  }
+
+  public void publishTagDeleted(Long tagId) {
+    if (!properties.isEnabled() || tagId == null) {
+      return;
+    }
+    publisher.publishEvent(new DeleteDocumentEvent(properties.tagsIndex(), tagId));
+  }
+}
diff --git a/backend/src/main/java/com/openisle/search/SearchIndexInitializer.java b/backend/src/main/java/com/openisle/search/SearchIndexInitializer.java
new file mode 100644
index 000000000..3f266d6a3
--- /dev/null
+++ b/backend/src/main/java/com/openisle/search/SearchIndexInitializer.java
@@ -0,0 +1,102 @@
+package com.openisle.search;
+
+import jakarta.annotation.PostConstruct;
+import java.io.IOException;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.opensearch.client.opensearch.OpenSearchClient;
+import org.opensearch.client.opensearch._types.mapping.Property;
+import org.opensearch.client.opensearch._types.mapping.TypeMapping;
+
+@Slf4j
+@RequiredArgsConstructor
+public class SearchIndexInitializer {
+
+  private final OpenSearchClient client;
+  private final OpenSearchProperties properties;
+
+  @PostConstruct
+  public void initialize() {
+    if (!properties.isEnabled() || !properties.isInitialize()) {
+      return;
+    }
+    ensureIndex(properties.postsIndex(), this::postMapping);
+    ensureIndex(properties.commentsIndex(), this::commentMapping);
+    ensureIndex(properties.usersIndex(), this::userMapping);
+    ensureIndex(properties.categoriesIndex(), this::categoryMapping);
+    ensureIndex(properties.tagsIndex(), this::tagMapping);
+  }
+
+  private void ensureIndex(String index, java.util.function.Supplier<TypeMapping> mappingSupplier) {
+    try {
+      boolean exists = client
+        .indices()
+        .exists(builder -> builder.index(index))
+        .value();
+      if (exists) {
+        return;
+      }
+      client.indices().create(builder -> builder.index(index).mappings(mappingSupplier.get()));
+      log.info("Created OpenSearch index {}", index);
+    } catch (IOException e) {
+      log.warn("Failed to initialize OpenSearch index {}", index, e);
+    }
+  }
+
+  private TypeMapping postMapping() {
+    return TypeMapping.of(builder ->
+      builder
+        .properties("type", Property.of(p -> p.keyword(k -> k)))
+        .properties("title", Property.of(p -> p.text(t -> t)))
+        .properties("content", Property.of(p -> p.text(t -> t)))
+        .properties("author", Property.of(p -> p.keyword(k -> k)))
+        .properties("category", Property.of(p -> p.keyword(k -> k)))
+        .properties("tags", Property.of(p -> p.keyword(k -> k)))
+        .properties("postId", Property.of(p -> p.long_(l -> l)))
+        .properties("createdAt", Property.of(p -> p.date(d -> d)))
+    );
+  }
+
+  private TypeMapping commentMapping() {
+    return TypeMapping.of(builder ->
+      builder
+        .properties("type", Property.of(p -> p.keyword(k -> k)))
+        .properties("title", Property.of(p -> p.text(t -> t)))
+        .properties("content", Property.of(p -> p.text(t -> t)))
+        .properties("author", Property.of(p -> p.keyword(k -> k)))
+        .properties("category", Property.of(p -> p.keyword(k -> k)))
+        .properties("tags", Property.of(p -> p.keyword(k -> k)))
+        .properties("postId", Property.of(p -> p.long_(l -> l)))
+        .properties("createdAt", Property.of(p -> p.date(d -> d)))
+    );
+  }
+
+  private TypeMapping userMapping() {
+    return TypeMapping.of(builder ->
+      builder
+        .properties("type", Property.of(p -> p.keyword(k -> k)))
+        .properties("title", Property.of(p -> p.text(t -> t)))
+        .properties("content", Property.of(p -> p.text(t -> t)))
+        .properties("createdAt", Property.of(p -> p.date(d -> d)))
+    );
+  }
+
+  private TypeMapping categoryMapping() {
+    return TypeMapping.of(builder ->
+      builder
+        .properties("type", Property.of(p -> p.keyword(k -> k)))
+        .properties("title", Property.of(p -> p.text(t -> t)))
+        .properties("content", Property.of(p -> p.text(t -> t)))
+    );
+  }
+
+  private TypeMapping tagMapping() {
+    return TypeMapping.of(builder ->
+      builder
+        .properties("type", Property.of(p -> p.keyword(k -> k)))
+        .properties("title", Property.of(p -> p.text(t -> t)))
+        .properties("content", Property.of(p -> p.text(t -> t)))
+        .properties("createdAt", Property.of(p -> p.date(d -> d)))
+    );
+  }
+}
diff --git a/backend/src/main/java/com/openisle/search/SearchIndexer.java b/backend/src/main/java/com/openisle/search/SearchIndexer.java
new file mode 100644
index 000000000..c9da039ed
--- /dev/null
+++ b/backend/src/main/java/com/openisle/search/SearchIndexer.java
@@ -0,0 +1,6 @@
+package com.openisle.search;
+
+public interface SearchIndexer {
+  void indexDocument(String index, SearchDocument document);
+  void deleteDocument(String index, Long id);
+}
diff --git a/backend/src/main/java/com/openisle/search/event/DeleteDocumentEvent.java b/backend/src/main/java/com/openisle/search/event/DeleteDocumentEvent.java
new file mode 100644
index 000000000..42c934a34
--- /dev/null
+++ b/backend/src/main/java/com/openisle/search/event/DeleteDocumentEvent.java
@@ -0,0 +1,3 @@
+package com.openisle.search.event;
+
+public record DeleteDocumentEvent(String index, Long id) {}
diff --git a/backend/src/main/java/com/openisle/search/event/IndexDocumentEvent.java b/backend/src/main/java/com/openisle/search/event/IndexDocumentEvent.java
new file mode 100644
index 000000000..3447bbd9e
--- /dev/null
+++ b/backend/src/main/java/com/openisle/search/event/IndexDocumentEvent.java
@@ -0,0 +1,5 @@
+package com.openisle.search.event;
+
+import com.openisle.search.SearchDocument;
+
+public record IndexDocumentEvent(String index, SearchDocument document) {}
diff --git a/backend/src/main/java/com/openisle/service/CategoryService.java b/backend/src/main/java/com/openisle/service/CategoryService.java
index 3d375e6e1..a9b7779af 100644
--- a/backend/src/main/java/com/openisle/service/CategoryService.java
+++ b/backend/src/main/java/com/openisle/service/CategoryService.java
@@ -3,6 +3,7 @@ package com.openisle.service;
 import com.openisle.config.CachingConfig;
 import com.openisle.model.Category;
 import com.openisle.repository.CategoryRepository;
+import com.openisle.search.SearchIndexEventPublisher;
 import java.util.List;
 import lombok.RequiredArgsConstructor;
 import org.springframework.cache.annotation.CacheEvict;
@@ -14,6 +15,7 @@ import org.springframework.stereotype.Service;
 public class CategoryService {
 
   private final CategoryRepository categoryRepository;
+  private final SearchIndexEventPublisher searchIndexEventPublisher;
 
   @CacheEvict(value = CachingConfig.CATEGORY_CACHE_NAME, allEntries = true)
   public Category createCategory(String name, String description, String icon, String smallIcon) {
@@ -22,7 +24,9 @@ public class CategoryService {
     category.setDescription(description);
     category.setIcon(icon);
     category.setSmallIcon(smallIcon);
-    return categoryRepository.save(category);
+    Category saved = categoryRepository.save(category);
+    searchIndexEventPublisher.publishCategorySaved(saved);
+    return saved;
   }
 
   @CacheEvict(value = CachingConfig.CATEGORY_CACHE_NAME, allEntries = true)
@@ -48,12 +52,15 @@ public class CategoryService {
     if (smallIcon != null) {
       category.setSmallIcon(smallIcon);
     }
-    return categoryRepository.save(category);
+    Category saved = categoryRepository.save(category);
+    searchIndexEventPublisher.publishCategorySaved(saved);
+    return saved;
   }
 
   @CacheEvict(value = CachingConfig.CATEGORY_CACHE_NAME, allEntries = true)
   public void deleteCategory(Long id) {
     categoryRepository.deleteById(id);
+    searchIndexEventPublisher.publishCategoryDeleted(id);
   }
 
   public Category getCategory(Long id) {
diff --git a/backend/src/main/java/com/openisle/service/CommentService.java b/backend/src/main/java/com/openisle/service/CommentService.java
index fd8d1d1f7..9da1af2d7 100644
--- a/backend/src/main/java/com/openisle/service/CommentService.java
+++ b/backend/src/main/java/com/openisle/service/CommentService.java
@@ -16,6 +16,7 @@ import com.openisle.repository.PointHistoryRepository;
 import com.openisle.repository.PostRepository;
 import com.openisle.repository.ReactionRepository;
 import com.openisle.repository.UserRepository;
+import com.openisle.search.SearchIndexEventPublisher;
 import com.openisle.service.NotificationService;
 import com.openisle.service.PointService;
 import com.openisle.service.SubscriptionService;
@@ -49,6 +50,7 @@ public class CommentService {
   private final PointHistoryRepository pointHistoryRepository;
   private final PointService pointService;
   private final ImageUploader imageUploader;
+  private final SearchIndexEventPublisher searchIndexEventPublisher;
 
   @CacheEvict(value = CachingConfig.POST_CACHE_NAME, allEntries = true)
   @Transactional
@@ -124,6 +126,7 @@ public class CommentService {
     }
     notificationService.notifyMentions(content, author, post, comment);
     log.debug("addComment finished for comment {}", comment.getId());
+    searchIndexEventPublisher.publishCommentSaved(comment);
     return comment;
   }
 
@@ -221,6 +224,7 @@ public class CommentService {
     }
     notificationService.notifyMentions(content, author, parent.getPost(), comment);
     log.debug("addReply finished for comment {}", comment.getId());
+    searchIndexEventPublisher.publishCommentSaved(comment);
     return comment;
   }
 
@@ -360,7 +364,9 @@ public class CommentService {
 
     // 逻辑删除评论
     Post post = comment.getPost();
+    Long commentId = comment.getId();
     commentRepository.delete(comment);
+    searchIndexEventPublisher.publishCommentDeleted(commentId);
     // 删除积分历史
     pointHistoryRepository.deleteAll(pointHistories);
 
diff --git a/backend/src/main/java/com/openisle/service/PostService.java b/backend/src/main/java/com/openisle/service/PostService.java
index 029c82882..c28566609 100644
--- a/backend/src/main/java/com/openisle/service/PostService.java
+++ b/backend/src/main/java/com/openisle/service/PostService.java
@@ -16,6 +16,7 @@ import com.openisle.repository.PostSubscriptionRepository;
 import com.openisle.repository.ReactionRepository;
 import com.openisle.repository.TagRepository;
 import com.openisle.repository.UserRepository;
+import com.openisle.search.SearchIndexEventPublisher;
 import com.openisle.service.EmailSender;
 import java.time.Duration;
 import java.time.LocalDateTime;
@@ -73,6 +74,8 @@ public class PostService {
   private final ConcurrentMap<Long, ScheduledFuture<?>> scheduledFinalizations =
     new ConcurrentHashMap<>();
 
+  private final SearchIndexEventPublisher searchIndexEventPublisher;
+
   @Value("${app.website-url:https://www.open-isle.com}")
   private String websiteUrl;
 
@@ -103,7 +106,8 @@ public class PostService {
     PostChangeLogService postChangeLogService,
     PointHistoryRepository pointHistoryRepository,
     @Value("${app.post.publish-mode:DIRECT}") PublishMode publishMode,
-    RedisTemplate redisTemplate
+    RedisTemplate redisTemplate,
+    SearchIndexEventPublisher searchIndexEventPublisher
   ) {
     this.postRepository = postRepository;
     this.userRepository = userRepository;
@@ -130,6 +134,7 @@ public class PostService {
     this.publishMode = publishMode;
 
     this.redisTemplate = redisTemplate;
+    this.searchIndexEventPublisher = searchIndexEventPublisher;
   }
 
   @EventListener(ApplicationReadyEvent.class)
@@ -346,6 +351,9 @@ public class PostService {
       );
       scheduledFinalizations.put(pp.getId(), future);
     }
+    if (post.getStatus() == PostStatus.PUBLISHED) {
+      searchIndexEventPublisher.publishPostSaved(post);
+    }
     return post;
   }
 
@@ -868,10 +876,12 @@ public class PostService {
       if (!tag.isApproved()) {
         tag.setApproved(true);
         tagRepository.save(tag);
+        searchIndexEventPublisher.publishTagSaved(tag);
       }
     }
     post.setStatus(PostStatus.PUBLISHED);
     post = postRepository.save(post);
+    searchIndexEventPublisher.publishPostSaved(post);
     notificationService.createNotification(
       post.getAuthor(),
       NotificationType.POST_REVIEWED,
@@ -895,13 +905,16 @@ public class PostService {
       if (!tag.isApproved()) {
         long count = postRepository.countDistinctByTags_Id(tag.getId());
         if (count <= 1) {
+          Long tagId = tag.getId();
           post.getTags().remove(tag);
           tagRepository.delete(tag);
+          searchIndexEventPublisher.publishTagDeleted(tagId);
         }
       }
     }
     post.setStatus(PostStatus.REJECTED);
     post = postRepository.save(post);
+    searchIndexEventPublisher.publishPostDeleted(post.getId());
     notificationService.createNotification(
       post.getAuthor(),
       NotificationType.POST_REVIEWED,
@@ -1042,6 +1055,9 @@ public class PostService {
     if (!oldTags.equals(newTags)) {
       postChangeLogService.recordTagChange(updated, user, oldTags, newTags);
     }
+    if (updated.getStatus() == PostStatus.PUBLISHED) {
+      searchIndexEventPublisher.publishPostSaved(updated);
+    }
     return updated;
   }
 
@@ -1094,8 +1110,10 @@ public class PostService {
       }
     }
     String title = post.getTitle();
+    Long postId = post.getId();
     postChangeLogService.deleteLogsForPost(post);
     postRepository.delete(post);
+    searchIndexEventPublisher.publishPostDeleted(postId);
     if (adminDeleting) {
       notificationService.createNotification(
         author,
diff --git a/backend/src/main/java/com/openisle/service/SearchService.java b/backend/src/main/java/com/openisle/service/SearchService.java
index dee83fed9..287815210 100644
--- a/backend/src/main/java/com/openisle/service/SearchService.java
+++ b/backend/src/main/java/com/openisle/service/SearchService.java
@@ -11,14 +11,26 @@ import com.openisle.repository.CommentRepository;
 import com.openisle.repository.PostRepository;
 import com.openisle.repository.TagRepository;
 import com.openisle.repository.UserRepository;
+import com.openisle.search.OpenSearchProperties;
+import com.openisle.search.SearchDocument;
+import java.io.IOException;
+import java.util.ArrayList;
 import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Map;
+import java.util.Optional;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.opensearch.client.opensearch.OpenSearchClient;
+import org.opensearch.client.opensearch._types.query_dsl.TextQueryType;
+import org.opensearch.client.opensearch.core.SearchResponse;
+import org.opensearch.client.opensearch.core.search.Hit;
 import org.springframework.stereotype.Service;
 
 @Service
+@Slf4j
 @RequiredArgsConstructor
 public class SearchService {
 
@@ -27,10 +39,14 @@ public class SearchService {
   private final CommentRepository commentRepository;
   private final CategoryRepository categoryRepository;
   private final TagRepository tagRepository;
+  private final Optional<OpenSearchClient> openSearchClient;
+  private final OpenSearchProperties openSearchProperties;
 
   @org.springframework.beans.factory.annotation.Value("${app.snippet-length}")
   private int snippetLength;
 
+  private static final int DEFAULT_OPEN_SEARCH_LIMIT = 50;
+
   public List<User> searchUsers(String keyword) {
     return userRepository.findByUsernameContainingIgnoreCase(keyword);
   }
@@ -64,6 +80,23 @@ public class SearchService {
   }
 
   public List<SearchResult> globalSearch(String keyword) {
+    if (keyword == null || keyword.isBlank()) {
+      return List.of();
+    }
+    if (isOpenSearchEnabled()) {
+      try {
+        List<SearchResult> results = searchWithOpenSearch(keyword);
+        if (!results.isEmpty()) {
+          return results;
+        }
+      } catch (IOException e) {
+        log.warn("OpenSearch global search failed, falling back to database query", e);
+      }
+    }
+    return fallbackGlobalSearch(keyword);
+  }
+
+  private List<SearchResult> fallbackGlobalSearch(String keyword) {
     Stream<SearchResult> users = searchUsers(keyword)
       .stream()
       .map(u ->
@@ -138,6 +171,143 @@ public class SearchService {
       .toList();
   }
 
+  private boolean isOpenSearchEnabled() {
+    return openSearchProperties.isEnabled() && openSearchClient.isPresent();
+  }
+
+  private List<SearchResult> searchWithOpenSearch(String keyword) throws IOException {
+    OpenSearchClient client = openSearchClient.orElse(null);
+    if (client == null) {
+      return List.of();
+    }
+    String trimmed = keyword.trim();
+    SearchResponse<SearchDocument> response = client.search(
+      builder ->
+        builder
+          .index(searchIndices())
+          .query(q ->
+            q.multiMatch(mm ->
+              mm
+                .query(trimmed)
+                .fields(List.of("title^3", "content^2", "author^2", "category", "tags"))
+                .type(TextQueryType.BestFields)
+            )
+          )
+          .highlight(h ->
+            h
+              .preTags("<mark>")
+              .postTags("</mark>")
+              .fields("content", f -> f.fragmentSize(highlightFragmentSize()).numberOfFragments(1))
+              .fields("title", f -> f.fragmentSize(highlightFragmentSize()).numberOfFragments(1))
+          )
+          .size(DEFAULT_OPEN_SEARCH_LIMIT),
+      SearchDocument.class
+    );
+    return mapHits(response.hits().hits(), trimmed);
+  }
+
+  private int highlightFragmentSize() {
+    int configured = openSearchProperties.getHighlightFragmentSize();
+    if (configured > 0) {
+      return configured;
+    }
+    if (snippetLength > 0) {
+      return snippetLength;
+    }
+    return 200;
+  }
+
+  private List<String> searchIndices() {
+    return List.of(
+      openSearchProperties.postsIndex(),
+      openSearchProperties.commentsIndex(),
+      openSearchProperties.usersIndex(),
+      openSearchProperties.categoriesIndex(),
+      openSearchProperties.tagsIndex()
+    );
+  }
+
+  private List<SearchResult> mapHits(List<Hit<SearchDocument>> hits, String keyword) {
+    List<SearchResult> results = new ArrayList<>();
+    for (Hit<SearchDocument> hit : hits) {
+      SearchResult result = mapHit(hit, keyword);
+      if (result != null) {
+        results.add(result);
+      }
+    }
+    return results;
+  }
+
+  private SearchResult mapHit(Hit<SearchDocument> hit, String keyword) {
+    SearchDocument document = hit.source();
+    if (document == null || document.entityId() == null) {
+      return null;
+    }
+    Map<String, List<String>> highlight = hit.highlight();
+    String highlightedContent = firstHighlight(highlight, "content");
+    String highlightedTitle = firstHighlight(highlight, "title");
+    boolean highlightTitle = highlightedTitle != null && !highlightedTitle.isBlank();
+    String documentType = document.type() != null ? document.type() : "";
+    String effectiveType = documentType;
+    if ("post".equals(documentType) && highlightTitle) {
+      effectiveType = "post_title";
+    }
+    String snippet = highlightedContent != null && !highlightedContent.isBlank()
+      ? cleanHighlight(highlightedContent)
+      : null;
+    if (snippet == null && highlightTitle) {
+      snippet = cleanHighlight(highlightedTitle);
+    }
+    boolean fromStart = "post_title".equals(effectiveType);
+    if (snippet == null || snippet.isBlank()) {
+      snippet = fallbackSnippet(document.content(), keyword, fromStart);
+    }
+    if (snippet == null) {
+      snippet = "";
+    }
+    String subText = null;
+    Long postId = null;
+    if ("post".equals(documentType) || "post_title".equals(effectiveType)) {
+      subText = document.category();
+    } else if ("comment".equals(documentType)) {
+      subText = document.author();
+      postId = document.postId();
+    }
+    return new SearchResult(
+      effectiveType,
+      document.entityId(),
+      document.title(),
+      subText,
+      snippet,
+      postId
+    );
+  }
+
+  private String firstHighlight(Map<String, List<String>> highlight, String field) {
+    if (highlight == null || field == null) {
+      return null;
+    }
+    List<String> values = highlight.get(field);
+    if (values == null || values.isEmpty()) {
+      return null;
+    }
+    return values.get(0);
+  }
+
+  private String cleanHighlight(String value) {
+    if (value == null) {
+      return null;
+    }
+    return value.replaceAll("<[^>]+>", "");
+  }
+
+  private String fallbackSnippet(String content, String keyword, boolean fromStart) {
+    if (content == null) {
+      return "";
+    }
+    return extractSnippet(content, keyword, fromStart);
+  }
+
   private String extractSnippet(String content, String keyword, boolean fromStart) {
     if (content == null) return "";
     int limit = snippetLength;
diff --git a/backend/src/main/java/com/openisle/service/TagService.java b/backend/src/main/java/com/openisle/service/TagService.java
index 0000f9d84..f7010a64b 100644
--- a/backend/src/main/java/com/openisle/service/TagService.java
+++ b/backend/src/main/java/com/openisle/service/TagService.java
@@ -5,6 +5,7 @@ import com.openisle.model.Tag;
 import com.openisle.model.User;
 import com.openisle.repository.TagRepository;
 import com.openisle.repository.UserRepository;
+import com.openisle.search.SearchIndexEventPublisher;
 import java.util.List;
 import lombok.RequiredArgsConstructor;
 import org.springframework.cache.annotation.CacheEvict;
@@ -20,6 +21,7 @@ public class TagService {
   private final TagRepository tagRepository;
   private final TagValidator tagValidator;
   private final UserRepository userRepository;
+  private final SearchIndexEventPublisher searchIndexEventPublisher;
 
   @CacheEvict(value = CachingConfig.TAG_CACHE_NAME, allEntries = true)
   public Tag createTag(
@@ -43,7 +45,9 @@ public class TagService {
         .orElseThrow(() -> new com.openisle.exception.NotFoundException("User not found"));
       tag.setCreator(creator);
     }
-    return tagRepository.save(tag);
+    Tag saved = tagRepository.save(tag);
+    searchIndexEventPublisher.publishTagSaved(saved);
+    return saved;
   }
 
   public Tag createTag(
@@ -78,12 +82,15 @@ public class TagService {
     if (smallIcon != null) {
       tag.setSmallIcon(smallIcon);
     }
-    return tagRepository.save(tag);
+    Tag saved = tagRepository.save(tag);
+    searchIndexEventPublisher.publishTagSaved(saved);
+    return saved;
   }
 
   @CacheEvict(value = CachingConfig.TAG_CACHE_NAME, allEntries = true)
   public void deleteTag(Long id) {
     tagRepository.deleteById(id);
+    searchIndexEventPublisher.publishTagDeleted(id);
   }
 
   public Tag approveTag(Long id) {
@@ -91,7 +98,9 @@ public class TagService {
       .findById(id)
       .orElseThrow(() -> new IllegalArgumentException("Tag not found"));
     tag.setApproved(true);
-    return tagRepository.save(tag);
+    Tag saved = tagRepository.save(tag);
+    searchIndexEventPublisher.publishTagSaved(saved);
+    return saved;
   }
 
   public List<Tag> listPendingTags() {
diff --git a/backend/src/main/java/com/openisle/service/UserService.java b/backend/src/main/java/com/openisle/service/UserService.java
index d76d986dc..b41b8fd46 100644
--- a/backend/src/main/java/com/openisle/service/UserService.java
+++ b/backend/src/main/java/com/openisle/service/UserService.java
@@ -5,6 +5,7 @@ import com.openisle.exception.FieldException;
 import com.openisle.model.Role;
 import com.openisle.model.User;
 import com.openisle.repository.UserRepository;
+import com.openisle.search.SearchIndexEventPublisher;
 import com.openisle.service.AvatarGenerator;
 import com.openisle.service.PasswordValidator;
 import com.openisle.service.UsernameValidator;
@@ -34,6 +35,7 @@ public class UserService {
   private final RedisTemplate redisTemplate;
 
   private final EmailSender emailService;
+  private final SearchIndexEventPublisher searchIndexEventPublisher;
 
   public User register(
     String username,
@@ -58,7 +60,9 @@ public class UserService {
       //            u.setVerificationCode(genCode());
       u.setRegisterReason(reason);
       u.setApproved(mode == com.openisle.model.RegisterMode.DIRECT);
-      return userRepository.save(u);
+      User saved = userRepository.save(u);
+      searchIndexEventPublisher.publishUserSaved(saved);
+      return saved;
     }
 
     // ── 再按邮箱查 ───────────────────────────────────────────
@@ -75,7 +79,9 @@ public class UserService {
       //            u.setVerificationCode(genCode());
       u.setRegisterReason(reason);
       u.setApproved(mode == com.openisle.model.RegisterMode.DIRECT);
-      return userRepository.save(u);
+      User saved = userRepository.save(u);
+      searchIndexEventPublisher.publishUserSaved(saved);
+      return saved;
     }
 
     // ── 完全新用户 ───────────────────────────────────────────
@@ -89,14 +95,18 @@ public class UserService {
     user.setAvatar(avatarGenerator.generate(username));
     user.setRegisterReason(reason);
     user.setApproved(mode == com.openisle.model.RegisterMode.DIRECT);
-    return userRepository.save(user);
+    User saved = userRepository.save(user);
+    searchIndexEventPublisher.publishUserSaved(saved);
+    return saved;
   }
 
   public User registerWithInvite(String username, String email, String password) {
     User user = register(username, email, password, "", com.openisle.model.RegisterMode.DIRECT);
     user.setVerified(true);
     //        user.setVerificationCode(genCode());
-    return userRepository.save(user);
+    User saved = userRepository.save(user);
+    searchIndexEventPublisher.publishUserSaved(saved);
+    return saved;
   }
 
   private String genCode() {
@@ -209,7 +219,9 @@ public class UserService {
       .findByUsername(username)
       .orElseThrow(() -> new com.openisle.exception.NotFoundException("User not found"));
     user.setRegisterReason(reason);
-    return userRepository.save(user);
+    User saved = userRepository.save(user);
+    searchIndexEventPublisher.publishUserSaved(saved);
+    return saved;
   }
 
   public User updateProfile(String currentUsername, String newUsername, String introduction) {
diff --git a/backend/src/main/resources/application.properties b/backend/src/main/resources/application.properties
index 00ccc0302..44ebbfbfe 100644
--- a/backend/src/main/resources/application.properties
+++ b/backend/src/main/resources/application.properties
@@ -45,6 +45,16 @@ app.user.replies-limit=${USER_REPLIES_LIMIT:50}
 # Length of extracted snippets for posts and search (-1 to disable truncation)
 app.snippet-length=${SNIPPET_LENGTH:200}
 
+# OpenSearch integration
+app.search.enabled=${SEARCH_ENABLED:true}
+app.search.host=${SEARCH_HOST:localhost}
+app.search.port=${SEARCH_PORT:9200}
+app.search.scheme=${SEARCH_SCHEME:http}
+app.search.username=${SEARCH_USERNAME:}
+app.search.password=${SEARCH_PASSWORD:}
+app.search.index-prefix=${SEARCH_INDEX_PREFIX:openisle}
+app.search.highlight-fragment-size=${SEARCH_HIGHLIGHT_FRAGMENT_SIZE:${SNIPPET_LENGTH:200}}
+
 # Captcha configuration
 app.captcha.enabled=${CAPTCHA_ENABLED:false}
 recaptcha.secret-key=${RECAPTCHA_SECRET_KEY:}
diff --git a/backend/src/test/java/com/openisle/service/CommentServiceTest.java b/backend/src/test/java/com/openisle/service/CommentServiceTest.java
index e52bdb7be..b40a96003 100644
--- a/backend/src/test/java/com/openisle/service/CommentServiceTest.java
+++ b/backend/src/test/java/com/openisle/service/CommentServiceTest.java
@@ -11,6 +11,7 @@ import com.openisle.repository.PointHistoryRepository;
 import com.openisle.repository.PostRepository;
 import com.openisle.repository.ReactionRepository;
 import com.openisle.repository.UserRepository;
+import com.openisle.search.SearchIndexEventPublisher;
 import com.openisle.service.PointService;
 import org.junit.jupiter.api.Test;
 
@@ -29,6 +30,7 @@ class CommentServiceTest {
     PointHistoryRepository pointHistoryRepo = mock(PointHistoryRepository.class);
     PointService pointService = mock(PointService.class);
     ImageUploader imageUploader = mock(ImageUploader.class);
+    SearchIndexEventPublisher searchIndexEventPublisher = mock(SearchIndexEventPublisher.class);
 
     CommentService service = new CommentService(
       commentRepo,
@@ -41,7 +43,8 @@ class CommentServiceTest {
       nRepo,
       pointHistoryRepo,
       pointService,
-      imageUploader
+      imageUploader,
+      searchIndexEventPublisher
     );
 
     when(commentRepo.countByAuthorAfter(eq("alice"), any())).thenReturn(3L);
diff --git a/backend/src/test/java/com/openisle/service/PostServiceTest.java b/backend/src/test/java/com/openisle/service/PostServiceTest.java
index 6d9a220b6..e57e8579b 100644
--- a/backend/src/test/java/com/openisle/service/PostServiceTest.java
+++ b/backend/src/test/java/com/openisle/service/PostServiceTest.java
@@ -6,6 +6,7 @@ import static org.mockito.Mockito.*;
 import com.openisle.exception.RateLimitException;
 import com.openisle.model.*;
 import com.openisle.repository.*;
+import com.openisle.search.SearchIndexEventPublisher;
 import java.time.LocalDateTime;
 import java.util.List;
 import java.util.Optional;
@@ -42,6 +43,7 @@ class PostServiceTest {
     PostChangeLogService postChangeLogService = mock(PostChangeLogService.class);
     PointHistoryRepository pointHistoryRepository = mock(PointHistoryRepository.class);
     RedisTemplate redisTemplate = mock(RedisTemplate.class);
+    SearchIndexEventPublisher searchIndexEventPublisher = mock(SearchIndexEventPublisher.class);
 
     PostService service = new PostService(
       postRepo,
@@ -67,7 +69,8 @@ class PostServiceTest {
       postChangeLogService,
       pointHistoryRepository,
       PublishMode.DIRECT,
-      redisTemplate
+      redisTemplate,
+      searchIndexEventPublisher
     );
     when(context.getBean(PostService.class)).thenReturn(service);
 
@@ -118,6 +121,7 @@ class PostServiceTest {
     PostChangeLogService postChangeLogService = mock(PostChangeLogService.class);
     PointHistoryRepository pointHistoryRepository = mock(PointHistoryRepository.class);
     RedisTemplate redisTemplate = mock(RedisTemplate.class);
+    SearchIndexEventPublisher searchIndexEventPublisher = mock(SearchIndexEventPublisher.class);
 
     PostService service = new PostService(
       postRepo,
@@ -143,7 +147,8 @@ class PostServiceTest {
       postChangeLogService,
       pointHistoryRepository,
       PublishMode.DIRECT,
-      redisTemplate
+      redisTemplate,
+      searchIndexEventPublisher
     );
     when(context.getBean(PostService.class)).thenReturn(service);
 
@@ -207,6 +212,7 @@ class PostServiceTest {
     PostChangeLogService postChangeLogService = mock(PostChangeLogService.class);
     PointHistoryRepository pointHistoryRepository = mock(PointHistoryRepository.class);
     RedisTemplate redisTemplate = mock(RedisTemplate.class);
+    SearchIndexEventPublisher searchIndexEventPublisher = mock(SearchIndexEventPublisher.class);
 
     PostService service = new PostService(
       postRepo,
@@ -232,7 +238,8 @@ class PostServiceTest {
       postChangeLogService,
       pointHistoryRepository,
       PublishMode.DIRECT,
-      redisTemplate
+      redisTemplate,
+      searchIndexEventPublisher
     );
     when(context.getBean(PostService.class)).thenReturn(service);
 
@@ -283,6 +290,7 @@ class PostServiceTest {
     PostChangeLogService postChangeLogService = mock(PostChangeLogService.class);
     PointHistoryRepository pointHistoryRepository = mock(PointHistoryRepository.class);
     RedisTemplate redisTemplate = mock(RedisTemplate.class);
+    SearchIndexEventPublisher searchIndexEventPublisher = mock(SearchIndexEventPublisher.class);
 
     PostService service = new PostService(
       postRepo,
@@ -308,7 +316,8 @@ class PostServiceTest {
       postChangeLogService,
       pointHistoryRepository,
       PublishMode.DIRECT,
-      redisTemplate
+      redisTemplate,
+      searchIndexEventPublisher
     );
     when(context.getBean(PostService.class)).thenReturn(service);
 
@@ -375,6 +384,7 @@ class PostServiceTest {
     PostChangeLogService postChangeLogService = mock(PostChangeLogService.class);
     PointHistoryRepository pointHistoryRepository = mock(PointHistoryRepository.class);
     RedisTemplate redisTemplate = mock(RedisTemplate.class);
+    SearchIndexEventPublisher searchIndexEventPublisher = mock(SearchIndexEventPublisher.class);
 
     PostService service = new PostService(
       postRepo,
@@ -400,7 +410,8 @@ class PostServiceTest {
       postChangeLogService,
       pointHistoryRepository,
       PublishMode.DIRECT,
-      redisTemplate
+      redisTemplate,
+      searchIndexEventPublisher
     );
     when(context.getBean(PostService.class)).thenReturn(service);
 
diff --git a/backend/src/test/java/com/openisle/service/SearchServiceTest.java b/backend/src/test/java/com/openisle/service/SearchServiceTest.java
index 59027b64d..3dbd5734a 100644
--- a/backend/src/test/java/com/openisle/service/SearchServiceTest.java
+++ b/backend/src/test/java/com/openisle/service/SearchServiceTest.java
@@ -9,7 +9,9 @@ import com.openisle.repository.CommentRepository;
 import com.openisle.repository.PostRepository;
 import com.openisle.repository.TagRepository;
 import com.openisle.repository.UserRepository;
+import com.openisle.search.OpenSearchProperties;
 import java.util.List;
+import java.util.Optional;
 import org.junit.jupiter.api.Test;
 import org.mockito.Mockito;
 
@@ -27,7 +29,9 @@ class SearchServiceTest {
       postRepo,
       commentRepo,
       categoryRepo,
-      tagRepo
+      tagRepo,
+      Optional.empty(),
+      new OpenSearchProperties()
     );
 
     Post post1 = new Post();