diff --git a/src/main/java/com/openisle/repository/NotificationRepository.java b/src/main/java/com/openisle/repository/NotificationRepository.java
index f0d538c49..0cbec0d60 100644
--- a/src/main/java/com/openisle/repository/NotificationRepository.java
+++ b/src/main/java/com/openisle/repository/NotificationRepository.java
@@ -18,4 +18,6 @@ public interface NotificationRepository extends JpaRepository<Notification, Long
     List<Notification> findByComment(Comment comment);
 
     void deleteByTypeAndFromUser(NotificationType type, User fromUser);
+
+    void deleteByTypeAndFromUserAndPost(NotificationType type, User fromUser, Post post);
 }
diff --git a/src/main/java/com/openisle/service/NotificationService.java b/src/main/java/com/openisle/service/NotificationService.java
index 561b59b28..93948d5c7 100644
--- a/src/main/java/com/openisle/service/NotificationService.java
+++ b/src/main/java/com/openisle/service/NotificationService.java
@@ -9,6 +9,8 @@ import com.openisle.service.EmailSender;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.stereotype.Service;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import org.springframework.transaction.annotation.Transactional;
+
 import java.util.Map;
 
 import java.util.regex.Pattern;
diff --git a/src/main/java/com/openisle/service/PostService.java b/src/main/java/com/openisle/service/PostService.java
index 2e124f3f4..c3293c4c9 100644
--- a/src/main/java/com/openisle/service/PostService.java
+++ b/src/main/java/com/openisle/service/PostService.java
@@ -26,6 +26,7 @@ import java.util.List;
 import org.springframework.data.domain.PageRequest;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Sort;
+import org.springframework.transaction.annotation.Transactional;
 
 @Service
 public class PostService {
@@ -143,6 +144,7 @@ public class PostService {
         return post;
     }
 
+    @Transactional
     public Post viewPost(Long id, String viewer) {
         Post post = postRepository.findById(id)
                 .orElseThrow(() -> new com.openisle.exception.NotFoundException("Post not found"));
@@ -164,9 +166,8 @@ public class PostService {
         if (viewer != null && !viewer.equals(post.getAuthor().getUsername())) {
             User viewerUser = userRepository.findByUsername(viewer).orElse(null);
             if (viewerUser != null) {
+                notificationRepository.deleteByTypeAndFromUserAndPost(NotificationType.POST_VIEWED, viewerUser, post);
                 notificationService.createNotification(post.getAuthor(), NotificationType.POST_VIEWED, post, null, null, viewerUser, null, null);
-            } else {
-                notificationService.createNotification(post.getAuthor(), NotificationType.POST_VIEWED, post, null, null, null, null, null);
             }
         }
         return post;
diff --git a/src/test/java/com/openisle/service/NotificationServiceTest.java b/src/test/java/com/openisle/service/NotificationServiceTest.java
index 59d43d5e4..c4ca007a1 100644
--- a/src/test/java/com/openisle/service/NotificationServiceTest.java
+++ b/src/test/java/com/openisle/service/NotificationServiceTest.java
@@ -168,4 +168,27 @@ class NotificationServiceTest {
         verify(email).sendEmail("a@a.com", "有人回复了你", "https://ex.com/posts/1#comment-2");
         verify(push).sendNotification(eq(user), contains("/posts/1#comment-2"));
     }
+
+    @Test
+    void postViewedNotificationDeletesOldOnes() {
+        NotificationRepository nRepo = mock(NotificationRepository.class);
+        UserRepository uRepo = mock(UserRepository.class);
+        ReactionRepository rRepo = mock(ReactionRepository.class);
+        EmailSender email = mock(EmailSender.class);
+        PushNotificationService push = mock(PushNotificationService.class);
+        Executor executor = Runnable::run;
+        NotificationService service = new NotificationService(nRepo, uRepo, email, push, rRepo, executor);
+        org.springframework.test.util.ReflectionTestUtils.setField(service, "websiteUrl", "https://ex.com");
+
+        User owner = new User();
+        User viewer = new User();
+        Post post = new Post();
+
+        when(nRepo.save(any(Notification.class))).thenAnswer(i -> i.getArgument(0));
+
+        service.createNotification(owner, NotificationType.POST_VIEWED, post, null, null, viewer, null, null);
+
+        verify(nRepo).deleteByTypeAndFromUserAndPost(NotificationType.POST_VIEWED, viewer, post);
+        verify(nRepo).save(any(Notification.class));
+    }
 }