diff --git a/module/task/lang/en.php b/module/task/lang/en.php
index 8124efd61b..82b2c77a7d 100644
--- a/module/task/lang/en.php
+++ b/module/task/lang/en.php
@@ -199,6 +199,7 @@ $lang->task->cannotDeleteParent    = 'Cannot delete parent task';
 $lang->task->error = new stdclass();
 $lang->task->error->consumedNumber   = '"Current Cost" must be numbers.';
 $lang->task->error->estimateNumber   = '"Estimates" must be numbers.';
+$lang->task->error->estimateMinus    = '"Estimates" should not be negative number.';
 $lang->task->error->consumedSmall    = '"Hours Cost" must be > the last number.';
 $lang->task->error->consumedThisTime = 'Please enter "Hours Cost"';
 $lang->task->error->left             = 'Please enter "Hours Left"';
diff --git a/module/task/lang/zh-cn.php b/module/task/lang/zh-cn.php
index f0e26822d3..97bcb727fd 100644
--- a/module/task/lang/zh-cn.php
+++ b/module/task/lang/zh-cn.php
@@ -199,6 +199,7 @@ $lang->task->cannotDeleteParent    = '不能删除父任务。';
 $lang->task->error                   = new stdclass();
 $lang->task->error->consumedNumber   = '"本次消耗"必须为数字';
 $lang->task->error->estimateNumber   = '"预计剩余"必须为数字';
+$lang->task->error->estimateMinus    = '"最初预计"不能为负数';
 $lang->task->error->consumedSmall    = '"已经消耗"必须大于之前消耗';
 $lang->task->error->consumedThisTime = '请填写"工时"';
 $lang->task->error->left             = '请填写"剩余"';
diff --git a/module/task/model.php b/module/task/model.php
index 08790cb842..f844d19645 100644
--- a/module/task/model.php
+++ b/module/task/model.php
@@ -22,6 +22,11 @@ class taskModel extends model
      */
     public function create($projectID)
     {
+        if($this->post->estimate < 0)
+        {    
+            dao::$errors[] = $this->lang->task->error->estimateMinus;
+            return false;
+        }
         $taskIdList = array();
         $taskFiles  = array();
         $this->loadModel('file');