The invention provides a transmission method and a transmission device for an instant messaging service heartbeat packet in an LTE system. Network-side proxy UE transmits an uplink heartbeat packet, The UE does not require periodical transmission of the uplink heartbeat packet to the network side, thereby reducing number of times of RRC connection establishment and release, greatly reducing signaling cost in RRC connection establishment and release processes, saving an air interface resource, and making other Internet services acquire more resources of physical resource blocks (PRB) and control channels.