diff --git a/request.go b/request.go
index 12b0cc6..fe10663 100644
--- a/request.go
+++ b/request.go
@@ -69,14 +69,21 @@ func (r *Request) getData() io.Reader {
 			urlValues.Add(key, value)
 		}
 		reqBody = urlValues.Encode()
-		r.Headers["Content-Type"] = "application/x-www-form-urlencoded"
+		if _, ex := r.Headers["Content-Type"]; !ex {
+			r.Headers["Content-Type"] = "application/x-www-form-urlencoded"
+		}
+
 	} else if r.Json != nil {
 		bytesData, _ := json.Marshal(r.Json)
 		reqBody = string(bytesData)
-		r.Headers["Content-Type"] = "application/json"
+		if _, ex := r.Headers["Content-Type"]; !ex {
+			r.Headers["Content-Type"] = "application/json"
+		}
 	} else if r.JsonByte != nil {
 		reqBody = string(r.JsonByte)
-		r.Headers["Content-Type"] = "application/json"
+		if _, ex := r.Headers["Content-Type"]; !ex {
+			r.Headers["Content-Type"] = "application/json"
+		}
 	}
 	return strings.NewReader(reqBody)
 }