diff --git a/lib/wx_pay/service.rb b/lib/wx_pay/service.rb
index d9b3fca..0dfb4bb 100644
--- a/lib/wx_pay/service.rb
+++ b/lib/wx_pay/service.rb
@@ -28,6 +28,7 @@ module WxPay
       params = {
         appid: options.delete(:appid) || WxPay.appid,
         partnerid: options.delete(:mch_id) || WxPay.mch_id,
+        key: options.delete(:key) || WxPay.key,
         package: 'Sign=WXPay',
         timestamp: Time.now.to_i.to_s
       }.merge(params)
--
libgit2 0.21.0