The invention provides a VOIP (Voice over Internet Protocol) gateway voice link backup method and system. The VOIP gateway voice link backup method comprises the following step: if necessary, performing link switch. The link switch comprises the following steps: judging whether on-line communication exists or not; if the on-line communication exists, saving the scene of the on-line communication, recording the related uri and roles in the on-line communication, switching to the port of a backup uplink, taking the port of the backup uplink as an uplink port, and building a new media data channel; judging whether a calling party exists in the saved scene; if the calling party exists, obtaining the recoded uri information to start an SIP (Session Initiation Protocol) link call, and interacting with an SIP server; if a called party exists in the saved scene, waiting for receiving calling request information, and interacting with the SIP server; associating the built new media data channel with an original communication terminal. According to the VOIP gateway voice link backup method and system, a data link is recovered by switching the original uplink port; the new SIP link and the media data channel are built by recovering voices; the media data channel is associated with the data channel of the original conversation terminal. Therefore, the original communication terminal can be used for receiving and sending media data through the new media data channel, and the purpose of backing up the VIOP gateway uplink and the link switch function are achieved.