diff --git a/webapp/services/MissionService.php b/webapp/services/MissionService.php
index 7a4e1ae2..ea61082a 100644
--- a/webapp/services/MissionService.php
+++ b/webapp/services/MissionService.php
@@ -549,15 +549,32 @@ class MissionService extends BaseService {
 
     private function refreshOfferRewardMission()
     {
-        $this->offerRewartdMission = myself()->_getNowTime();
-        $num = mt\Parameter::getVal('wanted_refresh_mission_num', 0);
+        $this->offerRewartdMission['refreshtime'] = myself()->_getNowTime();
         $sentMissions = array();
         foreach ($this->offerRewartdMission as $mission) {
             if ($mission['sendtime'] > 0) {
                 array_push($sentMissions, $mission);
             }
         }
+        if (empty($this->offerRewartdMission['missions'])) {
+            $this->offerRewartdMission['missions'] = array();
+        }
         $metas = mt\Task::getOfferRewardMissions($this->offerRewartdMission['missions']);
+        $num = min(count($metas), mt\Parameter::getVal('wanted_refresh_mission_num', 0));
+        if ($num > 0) {
+            $selectKeys = array_rand($metas, $num);
+            foreach ($selectKeys as $key) {
+                $meta = $metas[$key];
+                array_push($this->offerRewartdMission['missions'],
+                           array(
+                               'mission_id' => $meta['id'],
+                               'createtime' => myself()->_getNowTime(),
+                               'modifytime' => myself()->_getNowTime(),
+                               'sendtime' => 0,
+                               'objects' => array()
+                           ));
+            }
+        }
     }
 
     private function getOfferRewardMissionInfo($missionId)