参考技术AFD_CLOSE: Only valid on connection-oriented sockets (for example, SOCK_STREAM) When WSAAsyncSelect called, if socket connection has been closed. After remote system initiated graceful close, when no data currently available to receive (Be aware that, if data has been received and is waiting to be read when the remote system initiates a graceful close, the FD_CLOSE is not delivered until all pending data has been read). After local system initiates graceful close with shutdown and remote system has responded with "End of Data" notification (for example, TCP FIN), when no data currently available to receive. When remote system terminates connection (for example, sent TCP RST), and lParam will contain WSAECONNRESET error value. Note FD_CLOSE is not posted after closesocket is called. 希望对你能有所帮助。