IE对HTTP流的HEAD部分的MIME头 application/octet-stream 具有直接下载的特性，所以如下解决。



Response.Clear()

Response.ContentType = "application/octet-stream"

Response.AddHeader("Content-Disposition", "attachment;FileName=" + HttpUtility.UrlEncode(filename, System.Text.Encoding.UTF8))

Response.WriteFile(filepath+filname)

Response.End()