diff --git a/app/chat/model/ChatMessage.php b/app/chat/model/ChatMessage.php
index ff9ca90..437099f 100644
--- a/app/chat/model/ChatMessage.php
+++ b/app/chat/model/ChatMessage.php
@@ -24,7 +24,7 @@ class ChatMessage extends BaseModel
             foreach ($sessionIds as $k => $session_id) {
                 if($group_arr) {
                     foreach ($group_arr as $gk => &$group) {
-                        $group['session_id'] = '';
+                        $group['session_id'] = Random::build('alnum', 32);;
                         $group['chat_type'] = 2;
                         if ($session_id['chat_type'] == 2) {
                             if ($group['group_id'] == $session_id['group_id']) {
@@ -37,7 +37,7 @@ class ChatMessage extends BaseModel
         }else {
             if($group_arr) {
                 foreach ($group_arr as $gk => &$group) {
-                    $group['session_id'] = '';
+                    $group['session_id'] = Random::build('alnum', 32);;
                     $group['chat_type'] = 2;
                 }
             }