A method to maintain Network Address Translation (NAT) binding is provided. The method includes: an edge NAT router mapping a source address of a data packet from a mobile terminal to the source address of the edge NAT router, and mapping a destination address of the data packet from a computing device to the destination address of the mobile terminal, and maintaining the two address mapping relationships for a first time interval; the computing device sending a heartbeat packet to the mobile terminal according to a second time interval smaller than the first time interval, so a Time To Live set value progressively decreases to 0 as the heartbeat packet reaches the edge NAT router, thereby maintaining a link from the mobile terminal to the computing device, such that the heartbeat packet will not be sent down to the handheld device.