diff --git a/app/controllers/courses_controller.rb b/app/controllers/courses_controller.rb
index 21dac6ada..8fa46bda5 100644
--- a/app/controllers/courses_controller.rb
+++ b/app/controllers/courses_controller.rb
@@ -1133,6 +1133,21 @@ class CoursesController < ApplicationController
     end
   end
 
+  #切换身份
+  def switch_role
+    members = @course.members.where("user_id = #{params[:user_id]}")
+    unless members.blank?
+      #role = MemberRole.where("member_id = #{members.first.id} and role_id = #{params[:role]}").first
+      curr_role = MemberRole.find_by_member_id_and_role_id(members.first.id, params[:curr_role])
+      tar_role = MemberRole.find_by_member_id_and_role_id(members.first.id, params[:tar_role])
+      unless (curr_role.nil? || tar_role.nil?)
+        curr_role.update_column('is_current', 0)
+        tar_role.update_column('is_current', 1)
+      end
+    end
+    redirect_to course_path(@course)
+  end
+
   private
   def update_quotes attachment
     if attachment.copy_from
diff --git a/app/controllers/members_controller.rb b/app/controllers/members_controller.rb
index 4dc2c52f5..9c6f606f6 100644
--- a/app/controllers/members_controller.rb
+++ b/app/controllers/members_controller.rb
@@ -154,9 +154,11 @@ class MembersController < ApplicationController
             user_ids = attrs.delete(:user_ids)
             user_ids.each do |user_id|
               member =  Member.new(:role_ids => params[:membership][:role_ids], :user_id => user_id)
-              role = Role.find_by_id(params[:membership][:role_ids])
+
+              role_ids = attrs.delete(:role_ids)
+              #role = Role.find(params[:membership][:role_ids])
               # 这里的判断只能通过角色名，可以弄成常量
-              if role && (role.name == "学生" || role.name == "Student")
+              if role_ids && !role_ids.include?("9") && role_ids.include?("10")
                 StudentsForCourse.create(:student_id => user_id, :course_id =>@course.id)
               end
 
@@ -252,7 +254,10 @@ class MembersController < ApplicationController
         if (params[:membership][:role_ids])
           role = Role.find(params[:membership][:role_ids][0])
           # 这里的判断只能通过角色名，可以弄成常量
-          if role.name == "学生"  || role.name == "Student"
+          attrs = params[:membership].dup
+          role_ids = attrs.delete(:role_ids)
+
+          if role_ids && !role_ids.include?("9") && role_ids.include?("10")
             StudentsForCourse.create(:student_id => @member.user_id, :course_id =>@course.id)
           else
             joined = StudentsForCourse.where('student_id = ? and course_id = ?', @member.user_id,@course.id)
diff --git a/app/helpers/courses_helper.rb b/app/helpers/courses_helper.rb
index 42511f218..46ad4bb1c 100644
--- a/app/helpers/courses_helper.rb
+++ b/app/helpers/courses_helper.rb
@@ -274,14 +274,19 @@ module CoursesHelper
     #searchPeopleByRoles(project, TeacherRoles)
     members = []
     project.members.includes(:user).each do |m|
-      members << m  if m && m.user && m.user.allowed_to?(:as_teacher,project)
+      #members << m  if m && m.user && m.user.allowed_to?(:as_teacher,project)
+      members << m  if m && m.user && m.user.has_teacher_role(project)
     end
     members
   end
 
   def TeacherAndAssistantCount course
-    students_count = course.student.count
-    number = course.members.count - students_count
+    #students_count = course.student.count
+    #number = course.members.count - students_count
+    member_ids = course.members.includes(:user).blank? ? "(-1)" : "(" + course.members.includes(:user).map { |mem| mem.id}.join(",") + ")"
+    role_ids = "(3, 7, 9)"
+    number = MemberRole.where("member_id in #{member_ids} and role_id in #{role_ids}").count
+    #number = (searchTeacherAndAssistant course).count
   end
 
   def search_student_in_group(project, course_group_id)
@@ -811,6 +816,10 @@ module CoursesHelper
       result = l(:label_student)
     elsif role == "Manager"
       result = l(:field_admin)
+    elsif role.include?("TeachingAsistant") && role.include?("Student")
+      result = l(:label_TA) + " " + l(:label_student)
+    elsif role.include?("Teacher") && role.include?("Student")
+      result = l(:label_teacher) + " " + l(:label_student)
     end
     result
   end
@@ -894,5 +903,15 @@ module CoursesHelper
          resource_num*5 + journal_num + homework_journal_num ) desc limit 3;")
   end
 
+  #用户在该课程是否具有某个角色
+  def get_user_member_roles_course course, user, role
+    members = course.members.where("user_id = #{user.id}")
+    result = false
+    unless members.blank?
+      m_roles = MemberRole.where("member_id = #{members.first.id} and role_id = #{role}")
+    end
+    result = !m_roles.blank?
+    result
+  end
 end
 
diff --git a/app/models/member.rb b/app/models/member.rb
index 3cb70a8fe..cb15e067b 100644
--- a/app/models/member.rb
+++ b/app/models/member.rb
@@ -53,7 +53,15 @@ class Member < ActiveRecord::Base
 
     new_role_ids = ids - role_ids
     # Add new roles
-    new_role_ids.each {|id| member_roles << MemberRole.new(:role_id => id) }
+    if new_role_ids.include?(7) && new_role_ids.include?(10)
+      member_roles << MemberRole.new(:role_id => 7)
+      member_roles << MemberRole.new(:role_id => 10, :is_current => 0)
+    elsif new_role_ids.include?(9) && new_role_ids.include?(10)
+      member_roles << MemberRole.new(:role_id => 9)
+      member_roles << MemberRole.new(:role_id => 10, :is_current => 0)
+    else
+       new_role_ids.each {|id| member_roles << MemberRole.new(:role_id => id) }
+    end
     # Remove roles (Rails' #role_ids= will not trigger MemberRole#on_destroy)
     member_roles_to_destroy = member_roles.select {|mr| !ids.include?(mr.role_id)}
     if member_roles_to_destroy.any?
diff --git a/app/models/member_role.rb b/app/models/member_role.rb
index 4d493cb27..799720833 100644
--- a/app/models/member_role.rb
+++ b/app/models/member_role.rb
@@ -16,6 +16,7 @@
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 
 class MemberRole < ActiveRecord::Base
+  # multi_role 课程中的多重角色 0：单角色/学生，1：管理员&学生，2：教师&学生，3：教辅&学生
   belongs_to :member
   belongs_to :role
 
diff --git a/app/models/user.rb b/app/models/user.rb
index 996aa9be7..afd45e08b 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -823,7 +823,7 @@ class User < Principal
       # Find course membership
       membership = coursemembership(course)
       if membership
-        roles = membership.roles
+        roles = membership.roles.where("is_current = 1")
       else
         @role_non_member ||= Role.non_member
         roles << @role_non_member
@@ -918,6 +918,12 @@ class User < Principal
     end
   end
 
+  #是否具有老师角色
+  def has_teacher_role(course)
+    member = course.members.where("user_id = #{self.id}").first
+    role = MemberRole.where("member_id = #{member.id} and role_id in (3, 7, 9)")
+    !role.blank?
+  end
 
   # Return true if the user is allowed to do the specified action on a specific context
   # Action can be:
diff --git a/app/views/courses/_course_members.html.erb b/app/views/courses/_course_members.html.erb
index 9f15405dc..563cbfff3 100644
--- a/app/views/courses/_course_members.html.erb
+++ b/app/views/courses/_course_members.html.erb
@@ -36,7 +36,7 @@
           </li>
           <% @roles.each do |role| %>
               <li>
-                <%= radio_button_tag 'membership[role_ids][]', role.id, role.name == "学生" || role.name == "Student" %>
+                <%= check_box_tag 'membership[role_ids][]', role.id, role.name == "学生" || role.name == "Student", :id => "add_member_checkbox_#{role.id}" %>
                 <label ><%= zh_course_role(h role) %></label>
               </li>
           <% end %>
@@ -47,4 +47,36 @@
         </a>
       </div>
   <% end%>
-</div><!-- 右边 end-->
\ No newline at end of file
+</div><!-- 右边 end-->
+
+<script>
+    $(function() {
+        $("#add_member_checkbox_7").on('click', function(){
+            $("#add_member_checkbox_10").attr("checked",$("#add_member_checkbox_7").is(":checked"));
+            if($("#add_member_checkbox_7").is(":checked")) {
+                $("#add_member_checkbox_9").attr('disabled', 'disabled');
+            } else {
+                $("#add_member_checkbox_9").removeAttr('disabled');
+            }
+        });
+        $("#add_member_checkbox_9").on('click', function(){
+            $("#add_member_checkbox_10").attr("checked",$("#add_member_checkbox_9").is(":checked"));
+            if($("#add_member_checkbox_9").is(":checked")) {
+                $("#add_member_checkbox_7").attr('disabled', 'disabled');
+            } else {
+                $("#add_member_checkbox_7").removeAttr('disabled');
+            }
+        });
+        $("#add_member_checkbox_10").on('click', function(){
+            if($("#add_member_checkbox_10").is(":checked")) {
+                $("#add_member_checkbox_7").removeAttr('disabled');
+                $("#add_member_checkbox_9").removeAttr('disabled');
+            } else {
+                $("#add_member_checkbox_7").removeAttr('disabled');
+                $("#add_member_checkbox_9").removeAttr('disabled');
+                $("#add_member_checkbox_7").attr("checked",false);
+                $("#add_member_checkbox_9").attr("checked",false);
+            }
+        });
+    });
+</script>
\ No newline at end of file
diff --git a/app/views/courses/_member.html.erb b/app/views/courses/_member.html.erb
index 1bfe3cbd7..f23a74063 100644
--- a/app/views/courses/_member.html.erb
+++ b/app/views/courses/_member.html.erb
@@ -10,7 +10,7 @@
             ) do |f| %>
             <% @roles.each do |role| %>
                 <ul style="text-align: left;" class="ml45">
-                  <%= radio_button_tag 'membership[role_ids][]', role.id, member.roles.include?(role),
+                  <%= check_box_tag 'membership[role_ids][]', role.id, member.roles.include?(role), :id => "edit_member_role_#{member.id}_#{role.id}",
                                          :disabled => member.member_roles.detect { |mr| mr.role_id == role.id && !mr.inherited_from.nil? } %>
                   <label ><%= zh_course_role(h role) %></label>
                 </ul>
@@ -35,4 +35,38 @@
                           :data => (!User.current.admin? && member.include?(User.current) ? {:confirm => l(:text_own_membership_delete_confirmation)} : {confirm: l(:label_delete_confirm)}) if member.deletable? %>
       <% end%>
     </li>
-<% end%>
\ No newline at end of file
+
+    <script>
+        $(function() {
+            $("#edit_member_role_<%=member.id %>_7").on('click', function(){
+                $("#edit_member_role_<%=member.id %>_10").attr("checked",$("#edit_member_role_<%=member.id %>_7").is(":checked"));
+                if($("#edit_member_role_<%=member.id %>_7").is(":checked")) {
+                    $("#edit_member_role_<%=member.id %>_9").attr("checked",false);
+                    $("#edit_member_role_<%=member.id %>_9").attr('disabled', 'disabled');
+                } else {
+                    $("#edit_member_role_<%=member.id %>_9").removeAttr('disabled');
+                }
+            });
+            $("#edit_member_role_<%=member.id %>_9").on('click', function(){
+                $("#edit_member_role_<%=member.id %>_10").attr("checked",$("#edit_member_role_<%=member.id %>_9").is(":checked"));
+                if($("#edit_member_role_<%=member.id %>_9").is(":checked")) {
+                    $("#edit_member_role_<%=member.id %>_7").attr('disabled', 'disabled');
+                    $("#edit_member_role_<%=member.id %>_7").attr("checked",false);
+                } else {
+                    $("#edit_member_role_<%=member.id %>_7").removeAttr('disabled');
+                }
+            });
+            $("#edit_member_role_<%=member.id %>_10").on('click', function(){
+                if($("#edit_member_role_<%=member.id %>_10").is(":checked")) {
+                    $("#edit_member_role_<%=member.id %>_7").removeAttr('disabled');
+                    $("#edit_member_role_<%=member.id %>_9").removeAttr('disabled');
+                } else {
+                    $("#edit_member_role_<%=member.id %>_7").removeAttr('disabled');
+                    $("#edit_member_role_<%=member.id %>_9").removeAttr('disabled');
+                    $("#edit_member_role_<%=member.id %>_7").attr("checked",false);
+                    $("#edit_member_role_<%=member.id %>_9").attr("checked",false);
+                }
+            });
+        });
+    </script>
+<% end%>
diff --git a/app/views/layouts/_course_base_info.html.erb b/app/views/layouts/_course_base_info.html.erb
index 8994dab10..a6d267d76 100644
--- a/app/views/layouts/_course_base_info.html.erb
+++ b/app/views/layouts/_course_base_info.html.erb
@@ -55,8 +55,15 @@
     <span class=" mr15">学期：<span  class="sy_cblack"><%= current_time_and_term @course %></span></span>
     <span class=" mr15">单位：<span class="sy_cblack"><%= get_occupation_from_user(@course.teacher).blank? ? '无' : get_occupation_from_user(@course.teacher) %></span></span>
   </p>
-  <!--<a href="javascript:void(0);" class="sy_btn_orange mr10" > 教师身份</a>-->
-  <% unless is_teacher %>
+  <% is_TA = get_user_member_roles_course @course, User.current, 7 %>
+  <% is_TE = get_user_member_roles_course @course, User.current, 9 %>
+  <% is_ST = get_user_member_roles_course @course, User.current, 10 %>
+  <% if !is_teacher && (is_TA || is_TE)  %>
+      <%= link_to '教师身份', switch_role_course_path(@course, :user_id => User.current.id, :curr_role => 10, :tar_role => (is_TA ? 7 : 9)), :class => "sy_btn_orange mr10 fl" %>
+  <% elsif is_teacher && is_ST %>
+      <%= link_to '学生身份', switch_role_course_path(@course, :user_id => User.current.id, :curr_role => (is_TA ? 7 : 9), :tar_role => 10), :class => "sy_btn_orange mr10 fl" %>
+  <% end %>
+  <% unless (is_teacher || is_TA || is_TE) %>
       <div id="join_in_course_header"><%= join_in_course_header(@course, User.current) %></div>
   <% end %>
 </div>
diff --git a/config/routes.rb b/config/routes.rb
index 6c16dbd7d..cc75f8dab 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -1151,6 +1151,7 @@ RedmineApp::Application.routes.draw do
       get "homework_search"
       get "show_comparecode"
       get "statistics_course"
+      get "switch_role"
     end
     collection do
       match 'join_private_courses', :via => [:get, :post]
diff --git a/db/migrate/20160727065357_add_column_to_member_role.rb b/db/migrate/20160727065357_add_column_to_member_role.rb
index b551c18bd..861a32e27 100644
--- a/db/migrate/20160727065357_add_column_to_member_role.rb
+++ b/db/migrate/20160727065357_add_column_to_member_role.rb
@@ -1,16 +1,5 @@
 class AddColumnToMemberRole < ActiveRecord::Migration
   def change
-    add_column :member_roles, :multi_role, :integer, :default => 0
-
-    count = MemberRole.all.count / 30 + 2
-    transaction do
-      for i in 1 ... count do i
-        MemberRole.page(i).per(30).each do |mr|
-          if mr.role_id == 3
-            mr.update_column('multi_role', 1)
-          end
-        end
-      end
-    end
+    add_column :member_roles, :is_current, :integer, :default => 1
   end
 end
diff --git a/db/schema.rb b/db/schema.rb
index ac6ea0ca8..b8352dde1 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -1108,7 +1108,7 @@ ActiveRecord::Schema.define(:version => 20160727065357) do
     t.integer "member_id",                     :null => false
     t.integer "role_id",                       :null => false
     t.integer "inherited_from"
-    t.integer "multi_role",     :default => 0
+    t.integer "is_current",     :default => 1
   end
 
   add_index "member_roles", ["member_id"], :name => "index_member_roles_on_member_id"