1.引入Sockets

using System.Net.Sockets;

2.定义TcpClient

private TcpClient tcpClient; // TcpClient实例
private NetworkStream stream; // 网络流，用于与服务器通信

3.连接网口

tcpClient = new TcpClient(); // TcpClient实例
{
    try
    {
        tcpClient.Connect("IP地址", "端口号");
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

4.发送数据

byte[] b = Encoding.ASCII.GetBytes(liens);
stream = tcpClient.GetStream();

BinaryWriter writer = new BinaryWriter(stream);//写入流

writer.Write(b, 0, b.Length);

5.关闭连接

 tcpClient.Close();