https://www.cnblogs.com/guhuazhen/p/12073770.html
webservice上传文件大小限制
<configuration>
<system.webServer>
<security>
<requestFiltering>
<!--修改服务器允许最大长度-->
<requestLimits maxAllowedContentLength="1073741824"/>
</requestFiltering>
</security>
</system.webServer>
</configuration>
<httpRuntime maxRequestLength="204800" executionTimeout="600"/>