try

zb.js

@@ -223,7 +223,7 @@ function depthByRest(symbol,callback) {
 
 function getBalanceByRest() {
   const sign = signParamsStr(`accesskey=${APIKEY}&method=getAccountInfo`);
-  const url = `https://trade.zb.com/api/getAccountInfo?accesskey=${APIKEY}&method=getAccountInfo&sign=${sign}&reqTime=${Date.now()}`;
+  const url = `https://trade.zb.cn/api/getAccountInfo?accesskey=${APIKEY}&method=getAccountInfo&sign=${sign}&reqTime=${Date.now()}`;
   _request("GET", url, (err, data) => {
     if (err) {
       console.error(err);