diff --git a/src/main/java/com/example/g8backend/controller/CommentController.java b/src/main/java/com/example/g8backend/controller/CommentController.java
new file mode 100644
index 0000000..353a45d
--- /dev/null
+++ b/src/main/java/com/example/g8backend/controller/CommentController.java
@@ -0,0 +1,35 @@
+package com.example.g8backend.controller;
+
+import com.example.g8backend.entity.Comment;
+import com.example.g8backend.service.ICommentService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+
+@RestController
+@RequestMapping("/api/comments")
+public class CommentController {
+
+    @Autowired
+    private ICommentService commentService;
+
+    // 创建评论
+    @PostMapping
+    public void createComment(@RequestParam Long postId, @RequestParam Long userId,
+                              @RequestParam String content, @RequestParam(required = false) Long parentCommentId) {
+        commentService.createComment(postId, userId, content, parentCommentId);
+    }
+
+    // 获取某帖子下的所有评论，包括顶级评论及其子评论
+    @GetMapping("/post/{postId}")
+    public List<Comment> getCommentsByPostId(@PathVariable Long postId) {
+        return commentService.getCommentsByPostId(postId);
+    }
+
+    // 删除评论
+    @DeleteMapping("/{commentId}")
+    public void deleteComment(@PathVariable Long commentId) {
+        commentService.deleteComment(commentId);
+    }
+}
diff --git a/src/main/java/com/example/g8backend/dto/CommentDTO.java b/src/main/java/com/example/g8backend/dto/CommentDTO.java
new file mode 100644
index 0000000..d36e748
--- /dev/null
+++ b/src/main/java/com/example/g8backend/dto/CommentDTO.java
@@ -0,0 +1,12 @@
+package com.example.g8backend.dto;
+
+import java.util.List;
+
+public class CommentDTO {
+    private Long commentId;
+    private Long userId;
+    private String content;
+    private List<CommentDTO> replies;
+
+    // Getter and Setter
+}
diff --git a/src/main/java/com/example/g8backend/entity/Comment.java b/src/main/java/com/example/g8backend/entity/Comment.java
new file mode 100644
index 0000000..30fa763
--- /dev/null
+++ b/src/main/java/com/example/g8backend/entity/Comment.java
@@ -0,0 +1,73 @@
+package com.example.g8backend.entity;
+
+import java.sql.Timestamp;
+import java.util.List;
+
+public class Comment {
+    private Long commentId;            // 评论ID
+    private Long postId;               // 所属帖子ID
+    private Long userId;               // 评论用户ID
+    private String content;            // 评论内容
+    private Long parentCommentId;      // 父评论ID，如果是顶级评论则为NULL
+    private Timestamp createdAt;       // 评论时间
+
+    private List<Comment> replies;
+
+    // Getter and Setter
+    public Long getCommentId() {
+        return commentId;
+    }
+
+    public void setCommentId(Long commentId) {
+        this.commentId = commentId;
+    }
+
+    public Long getPostId() {
+        return postId;
+    }
+
+    public void setPostId(Long postId) {
+        this.postId = postId;
+    }
+
+    public Long getUserId() {
+        return userId;
+    }
+
+    public void setUserId(Long userId) {
+        this.userId = userId;
+    }
+
+    public String getContent() {
+        return content;
+    }
+
+    public void setContent(String content) {
+        this.content = content;
+    }
+
+    public Long getParentCommentId() {
+        return parentCommentId;
+    }
+
+    public void setParentCommentId(Long parentCommentId) {
+        this.parentCommentId = parentCommentId;
+    }
+
+    public Timestamp getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(Timestamp createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    // Getter and Setter for replies
+    public List<Comment> getReplies() {
+        return replies;
+    }
+
+    public void setReplies(List<Comment> replies) {
+        this.replies = replies;
+    }
+}
diff --git a/src/main/java/com/example/g8backend/mapper/CommentMapper.java b/src/main/java/com/example/g8backend/mapper/CommentMapper.java
new file mode 100644
index 0000000..b8fa1bf
--- /dev/null
+++ b/src/main/java/com/example/g8backend/mapper/CommentMapper.java
@@ -0,0 +1,26 @@
+package com.example.g8backend.mapper;
+
+import com.example.g8backend.entity.Comment;
+import org.apache.ibatis.annotations.*;
+
+import java.util.List;
+
+@Mapper
+public interface CommentMapper {
+
+    // 插入评论
+    @Insert("INSERT INTO comments (post_id, user_id, content, parent_comment_id) VALUES (#{postId}, #{userId}, #{content}, #{parentCommentId})")
+    int insert(Comment comment);
+
+    // 获取顶级评论
+    @Select("SELECT * FROM comments WHERE post_id = #{postId} AND parent_comment_id IS NULL ORDER BY created_at DESC")
+    List<Comment> findTopLevelCommentsByPostId(Long postId);
+
+    // 获取某个父评论ID对应的子评论
+    @Select("SELECT * FROM comments WHERE parent_comment_id = #{parentCommentId} ORDER BY created_at DESC")
+    List<Comment> findRepliesByParentCommentId(Long parentCommentId);
+
+    // 删除评论
+    @Delete("DELETE FROM comments WHERE comment_id = #{commentId}")
+    int deleteById(Long commentId);
+}
diff --git a/src/main/java/com/example/g8backend/service/ICommentService.java b/src/main/java/com/example/g8backend/service/ICommentService.java
new file mode 100644
index 0000000..ea82f8f
--- /dev/null
+++ b/src/main/java/com/example/g8backend/service/ICommentService.java
@@ -0,0 +1,16 @@
+package com.example.g8backend.service;
+
+import com.example.g8backend.entity.Comment;
+
+import java.util.List;
+
+public interface ICommentService {
+
+    void createComment(Long postId, Long userId, String content, Long parentCommentId);
+
+    List<Comment> getCommentsByPostId(Long postId);
+
+    List<Comment> getReplies(Long parentCommentId, int depth);
+
+    boolean deleteComment(Long commentId);
+}
diff --git a/src/main/java/com/example/g8backend/service/impl/CommentServiceImpl.java b/src/main/java/com/example/g8backend/service/impl/CommentServiceImpl.java
new file mode 100644
index 0000000..fae8a1f
--- /dev/null
+++ b/src/main/java/com/example/g8backend/service/impl/CommentServiceImpl.java
@@ -0,0 +1,70 @@
+package com.example.g8backend.service.impl;
+
+import com.example.g8backend.entity.Comment;
+import com.example.g8backend.mapper.CommentMapper;
+import com.example.g8backend.service.ICommentService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+
+import java.util.ArrayList;
+import java.util.List;
+
+
+@Service
+public class CommentServiceImpl implements ICommentService {
+
+    @Autowired
+    private CommentMapper commentMapper;
+
+    @Override
+    public void createComment(Long postId, Long userId, String content, Long parentCommentId) {
+        Comment comment = new Comment();
+        comment.setPostId(postId);
+        comment.setUserId(userId);
+        comment.setContent(content);
+        comment.setParentCommentId(parentCommentId); // 如果是顶级评论为NULL
+        commentMapper.insert(comment);
+    }
+
+    @Override
+// 获取帖子下的所有评论（顶级评论及其子评论）
+    public List<Comment> getCommentsByPostId(Long postId) {
+        // 获取顶级评论
+        List<Comment> topLevelComments = commentMapper.findTopLevelCommentsByPostId(postId);
+
+        // 获取每个评论的子评论
+        for (Comment comment : topLevelComments) {
+            List<Comment> replies = getReplies(comment.getCommentId(), 0); // 初始深度为0
+            comment.setReplies(replies);  // 设置子评论
+        }
+
+        return topLevelComments;
+    }
+
+
+    // 获取某个评论的子评论，并设置递归深度
+    public List<Comment> getReplies(Long parentCommentId, int depth) {
+        // 如果递归深度超过最大限制，停止递归
+        if (depth > 5) {
+            return new ArrayList<>();
+        }
+
+        // 获取当前评论的子评论
+        List<Comment> replies = commentMapper.findRepliesByParentCommentId(parentCommentId);
+
+        // 遍历每个子评论
+        for (Comment reply : replies) {
+            // 递归获取该子评论的子评论
+            List<Comment> childReplies = getReplies(reply.getCommentId(), depth + 1); // 深度加1
+            reply.setReplies(childReplies);  // 设置该子评论的子评论
+        }
+
+        return replies;
+    }
+
+
+    @Override
+    public boolean deleteComment(Long commentId) {
+        return commentMapper.deleteById(commentId) > 0;
+    }
+}
diff --git a/src/test/java/com/example/g8backend/service/CommentServiceTest.java b/src/test/java/com/example/g8backend/service/CommentServiceTest.java
new file mode 100644
index 0000000..f76880a
--- /dev/null
+++ b/src/test/java/com/example/g8backend/service/CommentServiceTest.java
@@ -0,0 +1,125 @@
+package com.example.g8backend.service;
+
+import com.example.g8backend.entity.Comment;
+import com.example.g8backend.mapper.CommentMapper;
+import com.example.g8backend.service.impl.CommentServiceImpl;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.springframework.test.context.junit.jupiter.SpringExtension;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.*;
+
+@ExtendWith(SpringExtension.class)
+@DisplayName("评论服务测试")
+class CommentServiceTest {
+
+    @Mock
+    private CommentMapper commentMapper;
+
+    @InjectMocks
+    private CommentServiceImpl commentService;
+
+    private Comment testComment;
+
+    @BeforeEach
+    void setUp() {
+        MockitoAnnotations.openMocks(this);
+        testComment = createTestComment();
+    }
+
+    private Comment createTestComment() {
+        Comment comment = new Comment();
+        comment.setCommentId(1L);
+        comment.setPostId(1L);
+        comment.setUserId(1L);
+        comment.setContent("测试评论内容");
+        return comment;
+    }
+
+    @Test
+    @DisplayName("创建评论-成功")
+    void createComment_ShouldSucceed() {
+        // Arrange
+        when(commentMapper.insert(any(Comment.class))).thenReturn(1);
+
+        // Act
+        commentService.createComment(1L, 1L, "测试评论内容", null);
+
+        // Assert
+        verify(commentMapper).insert(any(Comment.class));
+    }
+
+    @Test
+    @DisplayName("获取评论-根据帖子ID返回评论列表")
+    void getCommentsByPostId_ShouldReturnComments() {
+        // Arrange
+        List<Comment> expectedComments = Arrays.asList(testComment);
+        when(commentMapper.findTopLevelCommentsByPostId(1L)).thenReturn(expectedComments);
+
+        // Act
+        List<Comment> result = commentService.getCommentsByPostId(1L);
+
+        // Assert
+        assertNotNull(result);
+        assertFalse(result.isEmpty());
+        assertEquals(testComment.getCommentId(), result.get(0).getCommentId());
+        verify(commentMapper).findTopLevelCommentsByPostId(1L);
+    }
+
+    @Test
+    @DisplayName("删除评论-成功")
+    void deleteComment_ShouldSucceed() {
+        // Arrange
+        when(commentMapper.deleteById(1L)).thenReturn(1);
+
+        // Act
+        boolean result = commentService.deleteComment(1L);
+
+        // Assert
+        assertTrue(result);
+        verify(commentMapper).deleteById(1L);
+    }
+
+    @Test
+    @DisplayName("获取评论-没有评论")
+    void getCommentsByPostId_WhenNoComments_ShouldReturnEmptyList() {
+        // Arrange
+        when(commentMapper.findTopLevelCommentsByPostId(999L)).thenReturn(Arrays.asList());
+
+        // Act
+        List<Comment> result = commentService.getCommentsByPostId(999L);
+
+        // Assert
+        assertNotNull(result);
+        assertTrue(result.isEmpty());
+        verify(commentMapper).findTopLevelCommentsByPostId(999L);
+    }
+
+    @Test
+    @DisplayName("获取评论-根据父评论ID返回子评论")
+    void getReplies_ShouldReturnReplies() {
+        // Arrange
+        List<Comment> expectedReplies = Arrays.asList(testComment);
+        when(commentMapper.findRepliesByParentCommentId(1L)).thenReturn(expectedReplies);
+
+        // Act
+        List<Comment> result = commentService.getReplies(1L, 5);
+
+        // Assert
+        assertNotNull(result);
+        assertFalse(result.isEmpty());
+        assertEquals(testComment.getCommentId(), result.get(0).getCommentId());
+        verify(commentMapper).findRepliesByParentCommentId(1L);
+    }
+
+}