diff --git a/lib/wx_pay/service.rb b/lib/wx_pay/service.rb
index 15eb99a..d9b3fca 100644
--- a/lib/wx_pay/service.rb
+++ b/lib/wx_pay/service.rb
@@ -10,6 +10,7 @@ module WxPay
       params = {
         appid: options.delete(:appid) || WxPay.appid,
         mch_id: options.delete(:mch_id) || WxPay.mch_id,
+        key: options.delete(:key) || WxPay.key,
         nonce_str: SecureRandom.uuid.tr('-', '')
       }.merge(params)
 
--
libgit2 0.21.0