diff --git a/application/api/controller/UserWallet.php b/application/api/controller/UserWallet.php
index 596aac94..9e7993eb 100644
--- a/application/api/controller/UserWallet.php
+++ b/application/api/controller/UserWallet.php
@@ -58,6 +58,11 @@ class UserWallet extends BaseCom
     public function exchange_coin()
     {
         $earnings_num = input('earnings_num', 0);
+        //最少兑换钻石
+        $min_earnings_num = get_system_config_value('min_earnings_num');
+        if ($earnings_num < $min_earnings_num) {
+            return V(0, '兑换金额不能小于' . $min_earnings_num);
+        }
         $reslut = model('UserWallet')->exchange_coin($this->uid,$earnings_num);
         return V($reslut['code'], $reslut['msg'], $reslut['data']);
     }