using System.Net;

public FileStreamResult GetStreaem(string path)
{
var reqFtp = (FtpWebRequest)WebRequest.Create(new Uri(path));
reqFtp.Method = WebRequestMethods.Ftp.DownloadFile;
reqFtp.UseBinary = true;
//reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
reqFtp.UsePassive = false; //选择主动还是被动模式 , 这句要加上的。
reqFtp.KeepAlive = false;//一定要设置此属性，否则一次性下载多个文件的时候，会出现异常。
var response = (FtpWebResponse)reqFtp.GetResponse();
var ftpStream = response.GetResponseStream();
return File(ftpStream, "application/pdf", "ib70guide.pdf");
}