diff --git a/lib/http_proxy.js b/lib/http_proxy.js
index 49b4838..770c280 100644
--- a/lib/http_proxy.js
+++ b/lib/http_proxy.js
@@ -114,7 +114,7 @@ class HttpProxy {
         // urllib default use querystring to stringify form data which don't support nested object
         // will use qs instead of querystring to support nested object by set nestedQuerystring to true.
         options.nestedQuerystring = true;
-        options.data = requestBody;
+        options.data = rawBody || requestBody;
         // urllib wll auto set
         delete options.headers['content-length'];
       } else {