diff --git a/extend/pay/Epay.php b/extend/pay/Epay.php
index 9de924b..521349a 100644
--- a/extend/pay/Epay.php
+++ b/extend/pay/Epay.php
@@ -131,10 +131,14 @@ class Epay
     /**
      * API 模式下单（mapi.php）
      *
+     * @param string $clientIp 下单用户的 IP（mapi.php 必填，否则报 "用户IP地址(clientip)不能为空"）
      * @return array|null
      */
-    public function createOrderApi($orderNo, $type, $amount, $name, $notifyUrl, $returnUrl = '', $param = '')
+    public function createOrderApi($orderNo, $type, $amount, $name, $notifyUrl, $returnUrl = '', $param = '', $clientIp = '')
     {
+        if ($clientIp === '' || $clientIp === null) {
+            $clientIp = \think\Request::instance()->ip();
+        }
         $params = [
             'pid'          => strval($this->config['pid'] ?? ''),
             'type'         => $type,
@@ -144,6 +148,7 @@ class Epay
             'name'         => $name,
             'money'        => strval($amount),
             'param'        => $param,
+            'clientip'     => strval($clientIp),
             'sign_type'    => 'MD5',
         ];
         $params['sign'] = $this->generateSign($params);