diff --git a/trunk/module/search/lang/zh-cn.php b/trunk/module/search/lang/zh-cn.php
index cdf65c79b6..557f9ee85a 100644
--- a/trunk/module/search/lang/zh-cn.php
+++ b/trunk/module/search/lang/zh-cn.php
@@ -41,3 +41,5 @@ $lang->search->operators['include'] = '包含';
 
 $lang->search->andor['and']         = '并且';
 $lang->search->andor['or']          = '或者';
+
+$lang->search->null = '空';
diff --git a/trunk/module/search/model.php b/trunk/module/search/model.php
index 09c35e715f..dd88d6bd84 100644
--- a/trunk/module/search/model.php
+++ b/trunk/module/search/model.php
@@ -48,6 +48,7 @@ class searchModel extends model
 
             /* 对应的value为空，忽略。*/
             if($this->post->$valueName == false) continue; 
+            if($this->post->$valueName == 'null') $this->post->$valueName = '';
 
             /* 设置and, or。*/
             $andOr = strtoupper($this->post->$andOrName);
@@ -120,6 +121,7 @@ class searchModel extends model
             if($params[$fieldName]['values'] == 'users')    $params[$fieldName]['values']  = $users;
             if($params[$fieldName]['values'] == 'products') $params[$fieldName]['values']  = $products;
             if($params[$fieldName]['values'] == 'projects') $params[$fieldName]['values']  = $projects;
+            if(is_array($params[$fieldName]['values'])) $params[$fieldName]['values']  = $params[$fieldName]['values'] + array('null' => $this->lang->search->null);
         }
         return $params;
     }