diff --git a/app/views/shixuns/_shixun.json.jbuilder b/app/views/shixuns/_shixun.json.jbuilder
index f5ff0358b..e6dbd3115 100644
--- a/app/views/shixuns/_shixun.json.jbuilder
+++ b/app/views/shixuns/_shixun.json.jbuilder
@@ -15,7 +15,7 @@ json.array! shixuns do |shixun|
   json.status shixun.status
   json.power (current_user.shixun_permission(shixun)) # 现在首页只显示已发布的实训
   # REDO: 局部缓存
-  json.tag_name @tag_name_map&.fetch(shixun.id) || shixun.tag_repertoires.first.try(:name)
+  json.tag_name @tag_name_map&.fetch(shixun.id, nil) || shixun.tag_repertoires.first.try(:name)
   json.myshixuns_count shixun.myshixuns_count
   json.stu_num shixun.myshixuns_count
   json.score_info shixun.averge_star