diff --git a/partnerapi/shiip/model_request.go b/partnerapi/shiip/model_request.go
index 9a46c37..5ff69d9 100644
--- a/partnerapi/shiip/model_request.go
+++ b/partnerapi/shiip/model_request.go
@@ -55,3 +55,8 @@ type Label struct {
 	Caption string `json:"caption"`
 	URI     string `json:"uri"`
 }
+
+type AuthPayload struct {
+	ClientID     string `json:"clientId"`
+	ClientSecret string `json:"clientSecret"`
+}
diff --git a/partnerapi/shiip/shiip.go b/partnerapi/shiip/shiip.go
index 6ba7352..8b7c0e0 100644
--- a/partnerapi/shiip/shiip.go
+++ b/partnerapi/shiip/shiip.go
@@ -209,13 +209,10 @@ func (c *Client) CancelOutboundRequest(requestID int, note string) error {
 }
 
 func (c *Client) auth() (*authRes, error) {
-	// v := url.Values{}
-	// v.Add("realm", c.realm)
-	// v.Add("grant_type", "client_credentials")
-	// v.Add("client_id", c.clientID)
-	// v.Add("client_secret", c.clientSecret)
-	//
-	// body := v.Encode()
+	b := AuthPayload{
+		ClientID:     c.clientID,
+		ClientSecret: c.clientSecret,
+	}
 	header := map[string]string{
 		httputil.HeaderKeyContentType: httputil.HeaderValueApplicationJSON,
 	}
@@ -224,8 +221,8 @@ func (c *Client) auth() (*authRes, error) {
 		ResponseImmediately: true,
 		Payload: model.HttpRequest{
 			URL:    apiURL,
-			Method: http.MethodGet,
-			// Data:   body,
+			Method: http.MethodPost,
+			Data:   pjson.ToJSONString(b),
 			Header: header,
 		},
 	}