A method for redirecting network communication port and a network communication system thereof are disclosed. When a receiving end determines that a communication port needs to be redirected, the receiving end sends a redirected address to a transmitting end via a communication port. The redirected address includes redirected address information of a transport layer. According to the present invention, when the gatekeeper is not able to receive, via a well-known port, some of signaling sent from a node, the gatekeeper can inform the transmitting end to switch the port automatically, allowing thereby the node to continue the previous service. The present invention further allows the node to perform protocol switching automatically.