Method, host and system for sending control message

The invention provides a method, a host and a system for sending control message. The method comprises the following steps: the first host acquires the address of a rendezvous server connected with the second host; the first host constructs the control message, the destination host address in the control message is the address of the rendezvous server, and the destination host identification is the host identification of the second host; and the first host sends the control message to the rendezvous server to trigger the rendezvous server to send the control message to the second host according to the stored IP address of the second host and the host identification of the second host in the control message. The method, the host and the system can ensure the transmission of the control message, and further can ensure normal communication between the hosts of double communication parties according to the control message.