首先需要把[System.Web.Script.Services.ScriptService]前边的注释去掉，放开权限，其次需要在web.config 里<system.web节点下>添加

<webServices>
<protocols>
<add name="HttpGet"/>
<add name="HttpPost"/>
</protocols>
</webServices>

在外侧添加头信息的允许策略

<system.webServer>

<httpProtocol>
<customHeaders>
<add name="Access-Control-Allow-Origin" value="http://www.mamicode.com/*" />
<add name="Access-Control-Allow-Headers" value="http://www.mamicode.com/Origin, No-Cache, X-Requested-With, If-Modified-Since, Pragma, Last-Modified, Cache-Control, Expires, Content-Type, X-E4M-With" />
<add name="Access-Control-Allow-Methods" value="http://www.mamicode.com/GET, POST, PUT, DELETE" />
</customHeaders>
</httpProtocol>
</system.webServer>

asp.net webservice 跨域解决方法