diff --git a/db/update17.4.sql b/db/update17.4.sql
index 658ea1b080..36b545f067 100644
--- a/db/update17.4.sql
+++ b/db/update17.4.sql
@@ -1 +1,2 @@
-ALTER TABLE `zt_task` add `order` mediumint(8) NOT NULL AFTER `activatedDate`;
+ALTER TABLE `zt_task` ADD `order` mediumint(8) NOT NULL DEFAULT '0' AFTER `activatedDate`;
+ALTER TABLE `zt_task` ADD INDEX `order` (`order`);
diff --git a/db/zentao.sql b/db/zentao.sql
index 5cd07c3b2c..eab2fde60b 100755
--- a/db/zentao.sql
+++ b/db/zentao.sql
@@ -1537,6 +1537,7 @@ CREATE TABLE IF NOT EXISTS `zt_task` (
   KEY `story` (`story`),
   KEY `parent` (`parent`),
   KEY `assignedTo` (`assignedTo`)
+  KEY `order` (`order`)
 ) ENGINE=MyISAM DEFAULT CHARSET=utf8;
 -- DROP TABLE IF EXISTS `zt_taskestimate`;
 CREATE TABLE IF NOT EXISTS `zt_taskestimate` (
diff --git a/module/programplan/control.php b/module/programplan/control.php
index 2828763e31..e4e238c6ac 100644
--- a/module/programplan/control.php
+++ b/module/programplan/control.php
@@ -273,21 +273,19 @@ class programplan extends control
     /**
      * Save task drag action.
      *
+     * @param  int    $productID
+     *
+     * @access public
      * @access public
      * @return void
      */
-    public function ajaxSaveGanttMove()
+    public function ajaxSaveGanttMove($productID = 0)
     {
-        if($_POST)
+        if(!empty($_POST))
         {
-            $data        = fixer::input('post')->get();
-            $IdList      = explode('-', $data->id);
-            $executionID = $IdList[0];
-            $taskID      = $IdList[1];
-
-            return 1231231;
+            $this->loadModel('task')->saveTaskMove($productID);
+            if(dao::isError()) return $this->send(array('result' => 'fail', 'message' => dao::getError()));
+            return $this->send(array('result' => 'success'));
         }
-
-        return $this->send();
     }
 }
diff --git a/module/programplan/model.php b/module/programplan/model.php
index 4e4293e41b..4a4e475a9c 100755
--- a/module/programplan/model.php
+++ b/module/programplan/model.php
@@ -219,7 +219,7 @@ class programplanModel extends model
 
         if(empty($selectCustom)) $selectCustom = $this->loadModel('setting')->getItem("owner={$owner}&module={$module}&section={$section}&key={$object}");
 
-        $tasks     = $this->dao->select('*')->from(TABLE_TASK)->where('deleted')->eq(0)->andWhere('execution')->in($planIdList)->fetchAll('id');
+        $tasks     = $this->dao->select('*')->from(TABLE_TASK)->where('deleted')->eq(0)->andWhere('execution')->in($planIdList)->orderBy('execution_asc, order_asc, id_desc')->fetchAll('id');
         $taskTeams = $this->dao->select('root,account')->from(TABLE_TEAM)->where('type')->eq('task')->andWhere('root')->in(array_keys($tasks))->fetchGroup('root', 'account');
         $users     = $this->loadModel('user')->getPairs('noletter');
 
diff --git a/module/programplan/view/gantt.html.php b/module/programplan/view/gantt.html.php
index d3e5a20e13..0843e6157f 100644
--- a/module/programplan/view/gantt.html.php
+++ b/module/programplan/view/gantt.html.php
@@ -479,7 +479,6 @@ $(function()
     gantt.config.order_branch        = ganttType == 'assignedTo' ? false : 'marker';
     gantt.config.drag_progress       = false;
     gantt.config.drag_links          = false;
-    gantt.config.drag_resize         = false;
     gantt.config.smart_rendering     = true;
     gantt.config.smart_scales        = true;
     gantt.config.static_background   = true;
@@ -643,18 +642,20 @@ $(function()
         var link = createLink('programplan', 'ajaxSaveGanttMove');
 
         //prevent moving to another position.
-        if(task.parent != parent || id.indexOf('-') == -1) return false;
-
-        $.ajax({
+        if(task.parent != parent || id.indexOf('-') == -1)
+        {
+            return false;
+        }
+        else
+        {
+            $.ajax({
             url: link,
-            dataType: "json",
-            data: {id: id, type: task.type, order: tindex},
-            type: "post",
-            success: function(result)
-            {
-                var target = result;
-            }
-        });
+                dataType: "json",
+                data: {id: id, type: task.type, index: tindex},
+                type: "post",
+                success: function(result){}
+            });
+        }
 
         return true;
     });
diff --git a/module/task/model.php b/module/task/model.php
index 64652f828e..9450ad4d61 100644
--- a/module/task/model.php
+++ b/module/task/model.php
@@ -3988,4 +3988,74 @@ class taskModel extends model
 
         return true;
     }
+
+    /**
+     * Save task order.
+     *
+     * @param int     $productID
+     * @access public
+     * @return void
+     */
+    public function saveTaskMove($productID = 0)
+    {
+        $data         = fixer::input('post')->get();
+        $targetTaskID = explode('-', $data->dropTarget)[1];
+        $IdList       = explode('-', $data->id);
+        $executionID  = $IdList[0];
+        $taskID       = $IdList[1];
+        $index        = (int)$data->index;
+
+        $oldTask      = $this->loadModel('task')->getByID($taskID);
+        $targetTask   = $this->loadModel('task')->getByID($targetTaskID);
+        $execution    = $this->loadModel('execution')->getByID($executionID);
+        $tasks        = $this->dao->select('id')->from(TABLE_TASK)
+            ->where('execution')->eq($executionID)
+            ->andWhere('deleted')->eq(0)
+            ->beginIF($oldTask->parent <= 0)->andWhere('parent')->le(0)
+            ->beginIF($oldTask->parent > 0)->andWhere('parent')->eq($oldTask->parent)
+            ->fetchPairs('id');
+        $taskOrderSum = $this->dao->select('SUM(`order`) as sum')->from(TABLE_TASK)
+            ->where('deleted')->eq(0)
+            ->andWhere('execution')->eq($executionID)
+            ->beginIF($oldTask->parent <= 0)->andWhere('parent')->le(0)
+            ->beginIF($oldTask->parent > 0)->andWhere('parent')->eq($oldTask->parent)
+            ->fetch('sum');
+
+        if(!$taskOrderSum)
+        {
+            $order = 1;
+            foreach($tasks as $task)
+            {
+                $this->dao->update(TABLE_TASK)->set('`order`')->eq($order)->where('id')->eq($task)->exec();
+                $order ++;
+            }
+        }
+        else
+        {
+            $order    = ++ $index;
+            $oldOrder = (int)$oldTask->order;
+            if($order > $oldOrder)
+            {
+                $this->dao->update(TABLE_TASK)->set('`order`')->eq('`order`-1')
+                    ->where('execution')->eq($executionID)
+                    ->andWhere('`order`')->le($order)
+                    ->andWhere('`order`')->gt($oldOrder)
+                    ->beginIF($oldTask->parent <= 0)->andWhere('parent')->le(0)
+                    ->beginIF($oldTask->parent > 0)->andWhere('parent')->eq($oldTask->parent)
+                    ->exec();
+            }
+            else if($order < $oldOrder)
+            {
+                $this->dao->update(TABLE_TASK)->set('`order`=`order`+1')
+                    ->where('execution')->eq($executionID)
+                    ->andWhere('`order`')->lt($oldOrder)
+                    ->andWhere('`order`')->ge($order)
+                    ->beginIF($oldTask->parent <= 0)->andWhere('parent')->le(0)
+                    ->beginIF($oldTask->parent > 0)->andWhere('parent')->eq($oldTask->parent)
+                    ->exec();
+            }
+
+            $this->dao->update(TABLE_TASK)->set('`order`')->eq($order)->where('id')->eq($taskID)->exec();
+        }
+    }
 }