diff --git a/backend/src/main/java/com/openisle/controller/PostController.java b/backend/src/main/java/com/openisle/controller/PostController.java
index 86e27b06c..6c211fa29 100644
--- a/backend/src/main/java/com/openisle/controller/PostController.java
+++ b/backend/src/main/java/com/openisle/controller/PostController.java
@@ -217,11 +217,7 @@ public class PostController {
     //            userVisitService.recordVisit(auth.getName());
     //        }
 
-    return postService
-      .defaultListPosts(ids, tids, page, pageSize)
-      .stream()
-      .map(postMapper::toSummaryDto)
-      .collect(Collectors.toList());
+    return postMapper.toListDtos(postService.defaultListPosts(ids, tids, page, pageSize));
   }
 
   @GetMapping("/recent")
@@ -269,11 +265,7 @@ public class PostController {
     //            userVisitService.recordVisit(auth.getName());
     //        }
 
-    return postService
-      .listPostsByViews(ids, tids, page, pageSize)
-      .stream()
-      .map(postMapper::toSummaryDto)
-      .collect(Collectors.toList());
+    return postMapper.toListDtos(postService.listPostsByViews(ids, tids, page, pageSize));
   }
 
   @GetMapping("/latest-reply")
@@ -305,8 +297,7 @@ public class PostController {
     //            userVisitService.recordVisit(auth.getName());
     //        }
 
-    List<Post> posts = postService.listPostsByLatestReply(ids, tids, page, pageSize);
-    return posts.stream().map(postMapper::toSummaryDto).collect(Collectors.toList());
+    return postMapper.toListDtos(postService.listPostsByLatestReply(ids, tids, page, pageSize));
   }
 
   @GetMapping("/featured")
@@ -333,10 +324,6 @@ public class PostController {
     //        if (auth != null) {
     //            userVisitService.recordVisit(auth.getName());
     //        }
-    return postService
-      .listFeaturedPosts(ids, tids, page, pageSize)
-      .stream()
-      .map(postMapper::toSummaryDto)
-      .collect(Collectors.toList());
+    return postMapper.toListDtos(postService.listFeaturedPosts(ids, tids, page, pageSize));
   }
 }
diff --git a/backend/src/main/java/com/openisle/mapper/PostMapper.java b/backend/src/main/java/com/openisle/mapper/PostMapper.java
index 876b27863..24966f000 100644
--- a/backend/src/main/java/com/openisle/mapper/PostMapper.java
+++ b/backend/src/main/java/com/openisle/mapper/PostMapper.java
@@ -48,6 +48,38 @@ public class PostMapper {
     return dto;
   }
 
+  public List<PostSummaryDto> toListDtos(List<Post> posts) {
+    if (posts == null || posts.isEmpty()) {
+      return List.of();
+    }
+    Map<Long, List<User>> participantsMap = commentService.getParticipantsForPosts(posts, 5);
+    return posts
+      .stream()
+      .map(post -> {
+        PostSummaryDto dto = new PostSummaryDto();
+        applyListFields(post, dto);
+        List<User> participants = participantsMap.get(post.getId());
+        if (participants != null) {
+          dto.setParticipants(
+            participants.stream().map(userMapper::toAuthorDto).collect(Collectors.toList())
+          );
+        } else {
+          dto.setParticipants(List.of());
+        }
+        dto.setReactions(List.of());
+        return dto;
+      })
+      .collect(Collectors.toList());
+  }
+
+  public PostSummaryDto toListDto(Post post) {
+    PostSummaryDto dto = new PostSummaryDto();
+    applyListFields(post, dto);
+    dto.setParticipants(List.of());
+    dto.setReactions(List.of());
+    return dto;
+  }
+
   public PostDetailDto toDetailDto(Post post, String viewer) {
     PostDetailDto dto = new PostDetailDto();
     applyCommon(post, dto);
@@ -61,6 +93,25 @@ public class PostMapper {
     return dto;
   }
 
+  private void applyListFields(Post post, PostSummaryDto dto) {
+    dto.setId(post.getId());
+    dto.setTitle(post.getTitle());
+    dto.setContent(post.getContent());
+    dto.setCreatedAt(post.getCreatedAt());
+    dto.setAuthor(userMapper.toAuthorDto(post.getAuthor()));
+    dto.setCategory(categoryMapper.toDto(post.getCategory()));
+    dto.setTags(post.getTags().stream().map(tagMapper::toDto).collect(Collectors.toList()));
+    dto.setViews(post.getViews());
+    dto.setCommentCount(post.getCommentCount());
+    dto.setStatus(post.getStatus());
+    dto.setPinnedAt(post.getPinnedAt());
+    dto.setLastReplyAt(post.getLastReplyAt());
+    dto.setRssExcluded(post.getRssExcluded() == null || post.getRssExcluded());
+    dto.setClosed(post.isClosed());
+    dto.setVisibleScope(post.getVisibleScope());
+    dto.setType(post.getType());
+  }
+
   private void applyCommon(Post post, PostSummaryDto dto) {
     dto.setId(post.getId());
     dto.setTitle(post.getTitle());
diff --git a/backend/src/main/java/com/openisle/repository/CommentRepository.java b/backend/src/main/java/com/openisle/repository/CommentRepository.java
index 3a0d2fe50..ef7c56873 100644
--- a/backend/src/main/java/com/openisle/repository/CommentRepository.java
+++ b/backend/src/main/java/com/openisle/repository/CommentRepository.java
@@ -25,6 +25,13 @@ public interface CommentRepository extends JpaRepository<Comment, Long> {
     @org.springframework.data.repository.query.Param("post") Post post
   );
 
+  @org.springframework.data.jpa.repository.Query(
+    "SELECT DISTINCT c.post.id, c.author FROM Comment c WHERE c.post.id IN :postIds"
+  )
+  java.util.List<Object[]> findDistinctAuthorsByPostIds(
+    @org.springframework.data.repository.query.Param("postIds") java.util.List<Long> postIds
+  );
+
   @org.springframework.data.jpa.repository.Query(
     "SELECT MAX(c.createdAt) FROM Comment c WHERE c.post = :post"
   )
diff --git a/backend/src/main/java/com/openisle/repository/PostRepository.java b/backend/src/main/java/com/openisle/repository/PostRepository.java
index 107c692de..098787b3b 100644
--- a/backend/src/main/java/com/openisle/repository/PostRepository.java
+++ b/backend/src/main/java/com/openisle/repository/PostRepository.java
@@ -19,6 +19,8 @@ public interface PostRepository extends JpaRepository<Post, Long> {
   List<Post> findByStatusOrderByCreatedAtDesc(PostStatus status, Pageable pageable);
   List<Post> findByStatusOrderByViewsDesc(PostStatus status);
   List<Post> findByStatusOrderByViewsDesc(PostStatus status, Pageable pageable);
+  List<Post> findByStatusOrderByPinnedAtDescViewsDesc(PostStatus status, Pageable pageable);
+  List<Post> findByStatusOrderByPinnedAtDescLastReplyAtDesc(PostStatus status, Pageable pageable);
   List<Post> findByStatusAndCreatedAtGreaterThanEqualOrderByCreatedAtDesc(
     PostStatus status,
     LocalDateTime createdAt
@@ -43,6 +45,16 @@ public interface PostRepository extends JpaRepository<Post, Long> {
     PostStatus status,
     Pageable pageable
   );
+  List<Post> findByCategoryInAndStatusOrderByPinnedAtDescViewsDesc(
+    List<Category> categories,
+    PostStatus status,
+    Pageable pageable
+  );
+  List<Post> findByCategoryInAndStatusOrderByPinnedAtDescLastReplyAtDesc(
+    List<Category> categories,
+    PostStatus status,
+    Pageable pageable
+  );
   List<Post> findDistinctByTagsInAndStatus(List<Tag> tags, PostStatus status);
   List<Post> findDistinctByTagsInAndStatus(List<Tag> tags, PostStatus status, Pageable pageable);
   List<Post> findDistinctByTagsInAndStatusOrderByCreatedAtDesc(List<Tag> tags, PostStatus status);
@@ -132,6 +144,26 @@ public interface PostRepository extends JpaRepository<Post, Long> {
     Pageable pageable
   );
 
+  @Query(
+    "SELECT p FROM Post p JOIN p.tags t WHERE t IN :tags AND p.status = :status GROUP BY p.id HAVING COUNT(DISTINCT t.id) = :tagCount ORDER BY p.pinnedAt DESC, p.views DESC"
+  )
+  List<Post> findByAllTagsOrderByPinnedAtDescViewsDesc(
+    @Param("tags") List<Tag> tags,
+    @Param("status") PostStatus status,
+    @Param("tagCount") long tagCount,
+    Pageable pageable
+  );
+
+  @Query(
+    "SELECT p FROM Post p JOIN p.tags t WHERE t IN :tags AND p.status = :status GROUP BY p.id HAVING COUNT(DISTINCT t.id) = :tagCount ORDER BY p.pinnedAt DESC, p.lastReplyAt DESC"
+  )
+  List<Post> findByAllTagsOrderByPinnedAtDescLastReplyAtDesc(
+    @Param("tags") List<Tag> tags,
+    @Param("status") PostStatus status,
+    @Param("tagCount") long tagCount,
+    Pageable pageable
+  );
+
   @Query(
     "SELECT p FROM Post p JOIN p.tags t WHERE p.category IN :categories AND t IN :tags AND p.status = :status GROUP BY p.id HAVING COUNT(DISTINCT t.id) = :tagCount"
   )
@@ -174,6 +206,28 @@ public interface PostRepository extends JpaRepository<Post, Long> {
     Pageable pageable
   );
 
+  @Query(
+    "SELECT p FROM Post p JOIN p.tags t WHERE p.category IN :categories AND t IN :tags AND p.status = :status GROUP BY p.id HAVING COUNT(DISTINCT t.id) = :tagCount ORDER BY p.pinnedAt DESC, p.views DESC"
+  )
+  List<Post> findByCategoriesAndAllTagsOrderByPinnedAtDescViewsDesc(
+    @Param("categories") List<Category> categories,
+    @Param("tags") List<Tag> tags,
+    @Param("status") PostStatus status,
+    @Param("tagCount") long tagCount,
+    Pageable pageable
+  );
+
+  @Query(
+    "SELECT p FROM Post p JOIN p.tags t WHERE p.category IN :categories AND t IN :tags AND p.status = :status GROUP BY p.id HAVING COUNT(DISTINCT t.id) = :tagCount ORDER BY p.pinnedAt DESC, p.lastReplyAt DESC"
+  )
+  List<Post> findByCategoriesAndAllTagsOrderByPinnedAtDescLastReplyAtDesc(
+    @Param("categories") List<Category> categories,
+    @Param("tags") List<Tag> tags,
+    @Param("status") PostStatus status,
+    @Param("tagCount") long tagCount,
+    Pageable pageable
+  );
+
   @Query(
     "SELECT p FROM Post p JOIN p.tags t WHERE p.category IN :categories AND t IN :tags AND p.status = :status GROUP BY p.id HAVING COUNT(DISTINCT t.id) = :tagCount ORDER BY p.createdAt DESC"
   )
diff --git a/backend/src/main/java/com/openisle/service/CommentService.java b/backend/src/main/java/com/openisle/service/CommentService.java
index 908a5f30d..09c3c0e47 100644
--- a/backend/src/main/java/com/openisle/service/CommentService.java
+++ b/backend/src/main/java/com/openisle/service/CommentService.java
@@ -21,8 +21,12 @@ import com.openisle.service.NotificationService;
 import com.openisle.service.PointService;
 import com.openisle.service.SubscriptionService;
 import java.time.LocalDateTime;
+import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.HashSet;
+import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 import java.util.stream.Collectors;
 import lombok.RequiredArgsConstructor;
@@ -316,6 +320,37 @@ public class CommentService {
     return result;
   }
 
+  public Map<Long, List<User>> getParticipantsForPosts(List<Post> posts, int limit) {
+    if (posts == null || posts.isEmpty()) {
+      return Map.of();
+    }
+    Map<Long, LinkedHashSet<User>> map = new HashMap<>();
+    List<Long> postIds = new ArrayList<>(posts.size());
+    for (Post post : posts) {
+      postIds.add(post.getId());
+      LinkedHashSet<User> set = new LinkedHashSet<>();
+      set.add(post.getAuthor());
+      map.put(post.getId(), set);
+    }
+    for (Object[] row : commentRepository.findDistinctAuthorsByPostIds(postIds)) {
+      Long postId = (Long) row[0];
+      User author = (User) row[1];
+      LinkedHashSet<User> set = map.get(postId);
+      if (set != null) {
+        set.add(author);
+      }
+    }
+    Map<Long, List<User>> result = new HashMap<>(map.size());
+    for (Map.Entry<Long, LinkedHashSet<User>> entry : map.entrySet()) {
+      List<User> list = new ArrayList<>(entry.getValue());
+      if (list.size() > limit) {
+        list = list.subList(0, limit);
+      }
+      result.put(entry.getKey(), list);
+    }
+    return result;
+  }
+
   public java.util.List<Comment> getCommentsByIds(java.util.List<Long> ids) {
     log.debug("getCommentsByIds called for ids {}", ids);
     java.util.List<Comment> comments = commentRepository.findAllById(ids);
diff --git a/backend/src/main/java/com/openisle/service/PostService.java b/backend/src/main/java/com/openisle/service/PostService.java
index a55dcc4da..acea0b77d 100644
--- a/backend/src/main/java/com/openisle/service/PostService.java
+++ b/backend/src/main/java/com/openisle/service/PostService.java
@@ -339,6 +339,7 @@ public class PostService {
     post.setCategory(category);
     post.setTags(new HashSet<>(tags));
     post.setStatus(publishMode == PublishMode.REVIEW ? PostStatus.PENDING : PostStatus.PUBLISHED);
+    post.setLastReplyAt(LocalDateTime.now());
 
     // 什么都没设置的情况下，默认为ALL
     if (Objects.isNull(postVisibleScopeType)) {
@@ -809,9 +810,10 @@ public class PostService {
     boolean hasTags = tagIds != null && !tagIds.isEmpty();
 
     java.util.List<Post> posts;
+    Pageable pageable = buildPageable(page, pageSize);
 
     if (!hasCategories && !hasTags) {
-      posts = postRepository.findByStatusOrderByViewsDesc(PostStatus.PUBLISHED);
+      posts = postRepository.findByStatusOrderByPinnedAtDescViewsDesc(PostStatus.PUBLISHED, pageable);
     } else if (hasCategories) {
       java.util.List<Category> categories = categoryRepository.findAllById(categoryIds);
       if (categories.isEmpty()) {
@@ -822,16 +824,18 @@ public class PostService {
         if (tags.isEmpty()) {
           return java.util.List.of();
         }
-        posts = postRepository.findByCategoriesAndAllTagsOrderByViewsDesc(
+        posts = postRepository.findByCategoriesAndAllTagsOrderByPinnedAtDescViewsDesc(
           categories,
           tags,
           PostStatus.PUBLISHED,
-          tags.size()
+          tags.size(),
+          pageable
         );
       } else {
-        posts = postRepository.findByCategoryInAndStatusOrderByViewsDesc(
+        posts = postRepository.findByCategoryInAndStatusOrderByPinnedAtDescViewsDesc(
           categories,
-          PostStatus.PUBLISHED
+          PostStatus.PUBLISHED,
+          pageable
         );
       }
     } else {
@@ -839,10 +843,15 @@ public class PostService {
       if (tags.isEmpty()) {
         return java.util.List.of();
       }
-      posts = postRepository.findByAllTagsOrderByViewsDesc(tags, PostStatus.PUBLISHED, tags.size());
+      posts = postRepository.findByAllTagsOrderByPinnedAtDescViewsDesc(
+        tags,
+        PostStatus.PUBLISHED,
+        tags.size(),
+        pageable
+      );
     }
 
-    return paginate(sortByPinnedAndViews(posts), page, pageSize);
+    return posts;
   }
 
   public List<Post> listPostsByLatestReply(Integer page, Integer pageSize) {
@@ -859,9 +868,13 @@ public class PostService {
     boolean hasTags = tagIds != null && !tagIds.isEmpty();
 
     java.util.List<Post> posts;
+    Pageable pageable = buildPageable(page, pageSize);
 
     if (!hasCategories && !hasTags) {
-      posts = postRepository.findByStatusOrderByCreatedAtDesc(PostStatus.PUBLISHED);
+      posts = postRepository.findByStatusOrderByPinnedAtDescLastReplyAtDesc(
+        PostStatus.PUBLISHED,
+        pageable
+      );
     } else if (hasCategories) {
       java.util.List<Category> categories = categoryRepository.findAllById(categoryIds);
       if (categories.isEmpty()) {
@@ -872,16 +885,18 @@ public class PostService {
         if (tags.isEmpty()) {
           return java.util.List.of();
         }
-        posts = postRepository.findByCategoriesAndAllTagsOrderByCreatedAtDesc(
+        posts = postRepository.findByCategoriesAndAllTagsOrderByPinnedAtDescLastReplyAtDesc(
           categories,
           tags,
           PostStatus.PUBLISHED,
-          tags.size()
+          tags.size(),
+          pageable
         );
       } else {
-        posts = postRepository.findByCategoryInAndStatusOrderByCreatedAtDesc(
+        posts = postRepository.findByCategoryInAndStatusOrderByPinnedAtDescLastReplyAtDesc(
           categories,
-          PostStatus.PUBLISHED
+          PostStatus.PUBLISHED,
+          pageable
         );
       }
     } else {
@@ -889,14 +904,15 @@ public class PostService {
       if (tags.isEmpty()) {
         return new ArrayList<>();
       }
-      posts = postRepository.findByAllTagsOrderByCreatedAtDesc(
+      posts = postRepository.findByAllTagsOrderByPinnedAtDescLastReplyAtDesc(
         tags,
         PostStatus.PUBLISHED,
-        tags.size()
+        tags.size(),
+        pageable
       );
     }
 
-    return paginate(sortByPinnedAndLastReply(posts), page, pageSize);
+    return posts;
   }
 
   public List<Post> listPostsByCategories(
@@ -1394,6 +1410,13 @@ public class PostService {
       .toList();
   }
 
+  private Pageable buildPageable(Integer page, Integer pageSize) {
+    if (page == null || pageSize == null) {
+      return Pageable.unpaged();
+    }
+    return PageRequest.of(page, pageSize);
+  }
+
   private List<Post> paginate(List<Post> posts, Integer page, Integer pageSize) {
     if (page == null || pageSize == null) {
       return posts;
diff --git a/backend/src/main/resources/db/migration/V10__backfill_post_last_reply_at.sql b/backend/src/main/resources/db/migration/V10__backfill_post_last_reply_at.sql
new file mode 100644
index 000000000..ade69638d
--- /dev/null
+++ b/backend/src/main/resources/db/migration/V10__backfill_post_last_reply_at.sql
@@ -0,0 +1,4 @@
+-- Backfill last_reply_at for posts without comments to preserve latest-reply ordering
+UPDATE posts
+SET last_reply_at = created_at
+WHERE last_reply_at IS NULL;