diff --git a/src/main/java/com/wok/supportbot/service/DocumentService.java b/src/main/java/com/wok/supportbot/service/DocumentService.java
index 40f4a25..d3abc4c 100644
--- a/src/main/java/com/wok/supportbot/service/DocumentService.java
+++ b/src/main/java/com/wok/supportbot/service/DocumentService.java
@@ -108,9 +108,9 @@ public class DocumentService {
         // 0. 内容去重检查
         String contentHash = computeContentHash(content);
         if (contentHash != null) {
-            String duplicateTitle = checkContentDuplicate(contentHash);
+            String duplicateTitle = checkContentDuplicate(contentHash, categoryId);
             if (duplicateTitle != null) {
-                throw new RuntimeException("文档内容重复，已有同名文档: " + duplicateTitle);
+                throw new RuntimeException("文档内容重复，该分类下已有相同内容的文档: " + duplicateTitle);
             }
         }
 
@@ -1076,15 +1076,16 @@ public class DocumentService {
      * @param contentHash 内容哈希值
      * @return 重复文档的标题，如果不存在重复则返回 null
      */
-    private String checkContentDuplicate(String contentHash) {
+    private String checkContentDuplicate(String contentHash, Long categoryId) {
         if (contentHash == null) {
             return null;
         }
         QueryWrapper<KnowledgeDocument> wrapper = new QueryWrapper<>();
         wrapper.eq("content_hash", contentHash);
+        wrapper.eq("category_id", categoryId != null ? categoryId : 0L);
         wrapper.select("title");
-        KnowledgeDocument existing = documentMapper.selectOne(wrapper);
-        return existing != null ? existing.getTitle() : null;
+        List<KnowledgeDocument> existing = documentMapper.selectList(wrapper);
+        return existing != null && !existing.isEmpty() ? existing.get(0).getTitle() : null;
     }
 
     /**