private void SendFileStream(Socket socketStream, FileStream fs, byte[] byPack, string strFileName)
        {
            byte[] byHead = new byte[128];
            byHead[0] = byPack[0];
            byHead[1] = byPack[1];

            byte[] byFileName = encodingGB.GetBytes(strFileName);
            byHead[2] = Convert.ToByte(byFileName.Length);

            byFileName.CopyTo(byHead, 3);

            if (socketStream != null)
            {
                SocketSendMessage(socketStream, byHead);
            }
            else
            {
                MessageBox.Show("socket");
                return;
            }
            //socketStream.Send(byHead);

            byte[] byBody = new byte[PACKET_SIZE];            

            int nPackCount = Convert.ToInt32(byPack[0]) * Convert.ToInt32(byPack[1]);    

            int nCurrentPack = 0;        

            while (true)
            {
                if (socketStream != null)
                {
                    SocketReceiveMessage(socketStream);
                }              

               
                if (Convert.ToChar(byRec[0]) == 'E')
                {               
                    fs.Dispose();
                    fs.Close();
                    break;
                }
                else if (Convert.ToChar(byRec[0]) == 'S')
                {

                    nCurrentPack = Convert.ToInt32(byRec[1]) * 256 + Convert.ToInt32(byRec[2]);

                    fs.Seek((nCurrentPack - 1) * PACKET_SIZE, SeekOrigin.Begin);

                    byBody = new byte[PACKET_SIZE];
                    if ((nCurrentPack == nPackCount) && (nLastPackSize != 0))
                    {
                        fs.Read(byBody, 0, nLastPackSize);
                    }
                    else
                    {
                        fs.Read(byBody, 0, PACKET_SIZE);              

                    }

                    if (socketStream != null)
                    {
                        SocketSendMessage(socketStream, byBody);
                    }
                    else
                    {
                        MessageBox.Show("socket");
                        return;
                    }
                }


            }

        }

------解决方案--------------------
       public struct FilePack
       {
           /// <summary>
           /// 数据包大小
           /// </summary>
           public ushort PackSize;
         
           /// <summary>
           /// 文件GUID
           /// </summary>
           public byte[] FileGuid;  //16

           ///// <summary>
           ///// 包数据SHA1验证 ...  
           ///// </summary>
           //public byte[] PackSHA1;

           /// <summary>
           /// 包总数量
           /// </summary>
           public ushort PackCount;

           /// <summary>
           /// 包号
           /// </summary>
           public ushort PackIndex;          
          
           /// <summary>
           /// 包数据
           /// </summary>
           public byte[] PackData;
          
       }

这样发啊...

------解决方案--------------------