diff --git a/backend/app/services/knowledge_service.py b/backend/app/services/knowledge_service.py
index b9051e0..3e976d1 100644
--- a/backend/app/services/knowledge_service.py
+++ b/backend/app/services/knowledge_service.py
@@ -282,20 +282,20 @@ class KnowledgeService:
 
         total_count = len(items)
 
-        # 按 source_type 分组，初始化所有已知类别
-        type_groups: dict = {st: [] for st in self.SOURCE_TYPE_ORDER}
+        # 按 source_type 分组：仅收集有数据的类别，再按固定顺序排列
+        type_groups: dict = {}
         for item in items:
             st = item.source_type or "manual"
             if st not in type_groups:
                 type_groups[st] = []
             type_groups[st].append(item)
 
+        # 只遍历有数据的类别，按 SOURCE_TYPE_ORDER 顺序
         children = []
         for st in self.SOURCE_TYPE_ORDER:
-            st_items = type_groups.get(st, [])
-            # 空类别（0条）不渲染
-            if not st_items:
+            if st not in type_groups:
                 continue
+            st_items = type_groups[st]
 
             secondary_field = self.SECONDARY_GROUP_FIELD.get(st)
             grandchildren = []