The design is guided by computer network principal and achieves the Internet chat Which is based on WINSOCK. The software’s functions include chatting-room chat,broadcasted chat,point to point private chat,sound chat and transporting files. The Text mainly detailed on the technicals of chatting software and the designing, programming of the software for chatting tool, The development of the chatting tool mainly takes advantages of the network communication technicals,transporting files technicals,multiple threads technical on windows. The software is based on the communication of the WINSOCK, implementing the point to point chat, broadcasting chat and the files transporting. This chat tool runs on the any machine which supports the tcp/ip,upd or ftp protocol. because of the system’s C/S structure ,It needs to transport some control information between client and client, client and server. Transporting files,which is as an independent module,greatly adds up the functions of chatting tool.