WebClient client = new WebClient();第一种string URLAddress = @"http://files.cnblogs.com/x4646/tree.zip";string receivePath=@"C:\";client.DownloadFile(URLAddress, receivePath + System.IO.Path.GetFileName(URLAddress));就OK了。第二种　Stream str = client.OpenRead(URLAddress);   StreamReader reader = new StreamReader(str);   byte[] mbyte = new byte[1000000];   int allmybyte = (int)mbyte.Length;   int startmbyte = 0;   while (allmybyte > 0)   {    int m = str.Read(mbyte, startmbyte, allmybyte);    if (m == 0)     break;    startmbyte += m;    allmybyte -= m;   }   reader.Dispose();   str.Dispose();   string path = receivePath + System.IO.Path.GetFileName(URLAddress);   FileStream fstr = new FileStream(path, FileMode.OpenOrCreate, FileAccess.Write);   fstr.Write(mbyte, 0, startmbyte);   fstr.Flush();   fstr.Close();