//解决方法：

//引入命名空间：
using System.Security.Cryptography.X509Certificates;
using System.Net.Security;


//定义方法：

private static bool RemoteCertificateValidate(object sender, X509Certificate cert, X509Chain chain, SslPolicyErrors error)
{
    //为了通过证书验证，总是返回true
    return true;
}


//调用方法一：

//在构造函数中调用：

static WxRequest()
{
    // 获取验证证书的回调函数
    ServicePointManager.ServerCertificateValidationCallback+=RemoteCertificateValidate;
}

//方法二：

//在WebRequest请求之前调用：

ServicePointManager.ServerCertificateValidationCallback+=RemoteCertificateValidate;