diff --git a/app/views/users/_course_homework.html.erb b/app/views/users/_course_homework.html.erb
index 3a23c9f88..c8ff3aad2 100644
--- a/app/views/users/_course_homework.html.erb
+++ b/app/views/users/_course_homework.html.erb
@@ -1,6 +1,6 @@
 <% is_teacher = User.current.allowed_to?(:as_teacher,activity.course) %>
 <div class="resources mt10" id="user_activity_<%= user_activity_id%>">
-  <% cache [:user_homework_activity,activity.id.to_s+"-"+User.current.logged?.to_s+"-"+is_teacher.to_s+"-"+course_activity.to_s+"-"+(User.current.member_of_course?(activity.course)).to_s+"-"+activity.updated_at.to_i.to_s] do%>
+  <% cache [:user_homework_activity,activity.id.to_s+"-"+User.current.logged?.to_s+"-"+is_teacher.to_s+"-"+(User.current.member_of_course?(activity.course)).to_s+"-"+activity.updated_at.to_i.to_s] do%>
   <div class="homepagePostBrief">
     <div class="homepagePostPortrait">
       <%= link_to image_tag(url_to_avatar(activity.user), :width => "50", :height => "50"), user_path(activity.user_id), :alt => "用户头像" %>