diff --git a/wchat/common/HttpClient.php b/wchat/common/HttpClient.php
index 2316256..b0448e3 100644
--- a/wchat/common/HttpClient.php
+++ b/wchat/common/HttpClient.php
@@ -581,6 +581,9 @@ class HttpClient
 		} else if (isset($this->header['content-type'])) {
 			$contentType = $this->header['content-type'];
 		}
+		if ($contentType == 'multipart/form-data') {
+			return $data;
+		}
 
 		if (strpos($contentType, 'json') !== false) {
 			return Help::toJson($data);