diff --git a/src/main/java/com/pt/service/CommentService.java b/src/main/java/com/pt/service/CommentService.java
new file mode 100644
index 0000000..3d8b7dd
--- /dev/null
+++ b/src/main/java/com/pt/service/CommentService.java
@@ -0,0 +1,40 @@
+package com.pt.service;
+
+import com.pt.entity.Comment;
+import com.pt.repository.CommentRepository;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+
+import java.util.List;
+
+@Service
+public class CommentService {
+
+    @Autowired
+    private CommentRepository commentRepository;
+
+    public CommentService(CommentRepository commentRepository) {
+        this.commentRepository = commentRepository;
+    }
+
+    public void addComment(String content, String username, int postId) {
+        Comment comment = new Comment();
+        comment.setContent(content);
+        comment.setWriter(username);
+        comment.setParentPost(postId);
+        commentRepository.save(comment);
+    }
+
+    public void deleteComment(int commentId) {
+        commentRepository.deleteById(commentId);
+    }
+
+    public List<Comment> getCommentsByPostId(int postId) {
+        List<Comment> comments = commentRepository.findByParentPost(postId);
+        comments.sort(
+                // Sort comments by publish date in descending order
+                (c1, c2) -> c2.getPublishDate().compareTo(c1.getPublishDate())
+        );
+        return comments;
+    }
+}