diff --git a/app/controllers/courses_controller.rb b/app/controllers/courses_controller.rb
index e24a7386d..0ee9dc968 100644
--- a/app/controllers/courses_controller.rb
+++ b/app/controllers/courses_controller.rb
@@ -470,23 +470,27 @@ class CoursesController < ApplicationController
   end
 
   def homework
-    @offset, @limit = api_offset_and_limit({:limit => 10})
-    @bids = @course.homeworks.order('deadline DESC')
-    @bids = @bids.like(params[:name]) if params[:name].present?
-    @bid_count = @bids.count
-    @bid_pages = Paginator.new @bid_count, @limit, params['page']
-
-    @offset ||= @bid_pages.reverse_offset
-    unless @offset == 0
-      @bids = @bids.offset(@offset).limit(@limit).all.reverse
+    if @course.is_public == 0
+      render_403
     else
-      limit = @bid_count % @limit
-      if limit == 0
-        limit = 10
+      @offset, @limit = api_offset_and_limit({:limit => 10})
+      @bids = @course.homeworks.order('deadline DESC')
+      @bids = @bids.like(params[:name]) if params[:name].present?
+      @bid_count = @bids.count
+      @bid_pages = Paginator.new @bid_count, @limit, params['page']
+
+      @offset ||= @bid_pages.reverse_offset
+      unless @offset == 0
+        @bids = @bids.offset(@offset).limit(@limit).all.reverse
+      else
+        limit = @bid_count % @limit
+        if limit == 0
+          limit = 10
+        end
+        @bids = @bids.offset(@offset).limit(limit).all.reverse
       end
-      @bids = @bids.offset(@offset).limit(limit).all.reverse
+      render :layout => 'base_courses'
     end
-    render :layout => 'base_courses'
    end
 
   # 新建作业
diff --git a/app/helpers/watchers_helper.rb b/app/helpers/watchers_helper.rb
index 56b2ec0f4..155485b4c 100644
--- a/app/helpers/watchers_helper.rb
+++ b/app/helpers/watchers_helper.rb
@@ -97,7 +97,7 @@ module WatchersHelper
     return '' unless user && user.logged?
     # modify by nwb
     # 主讲教师不允许退出课程
-    return '' if user.id == course.tea_id
+    return '' if user.id == course.tea_id || course.is_public == 0
     joined = user.member_of_course?(course)
     text = joined ? l(:label_exit_course) : l(:label_join_course)
     url_t = join_path(:object_id => course.id)
diff --git a/app/views/layouts/base_courses.html.erb b/app/views/layouts/base_courses.html.erb
index 4554b0466..906574b9e 100644
--- a/app/views/layouts/base_courses.html.erb
+++ b/app/views/layouts/base_courses.html.erb
@@ -78,7 +78,6 @@
                             <%= link_to l(:label_course_modify_settings), {:controller => 'courses', :action => 'settings', :id => @course} %>
                             <%= render :partial => 'courses/set_course_time', :locals => {:course => @course} %>
                         <% else %>
-
                             <%= join_in_course(@course, User.current) %>
                         <% end %>
                         <% unless User.current.member_of_course?(@course) %>