diff --git a/wchat/common/Config.php b/wchat/common/Config.php
index 221de52..1fdbdc9 100644
--- a/wchat/common/Config.php
+++ b/wchat/common/Config.php
@@ -116,6 +116,10 @@ class Config
     private string $ssl_ca   = '';
     private int    $port     = 443;
 
+
+    private string $mchCert = '';
+    private string $mchKey = '';
+
     /**
      * @var string
      */
@@ -124,6 +128,38 @@ class Config
     private string $agent        = '';
     private bool   $usrSwoole    = false;
 
+    /**
+     * @return string
+     */
+    public function getMchCert(): string
+    {
+        return $this->mchCert;
+    }
+
+    /**
+     * @param string $mchCert
+     */
+    public function setMchCert(string $mchCert): void
+    {
+        $this->mchCert = $mchCert;
+    }
+
+    /**
+     * @return string
+     */
+    public function getMchKey(): string
+    {
+        return $this->mchKey;
+    }
+
+    /**
+     * @param string $mchKey
+     */
+    public function setMchKey(string $mchKey): void
+    {
+        $this->mchKey = $mchKey;
+    }
+
     /**
      * @return string
      */
diff --git a/wchat/wx/V3/WxV3PaymentTait.php b/wchat/wx/V3/WxV3PaymentTait.php
index 8634964..c64d5d5 100644
--- a/wchat/wx/V3/WxV3PaymentTait.php
+++ b/wchat/wx/V3/WxV3PaymentTait.php
@@ -56,7 +56,7 @@ trait WxV3PaymentTait
      */
     public function openssl_signature($body): string
     {
-        $pem = file_get_contents($this->getConfig()->getSslCert());
+        $pem = file_get_contents($this->getConfig()->getMchKey());
 
         $mch_private_key = openssl_get_privatekey($pem);