The invention relates to a method for realizing forever online PS service and relative device. Wherein, it comprises: first, when the user of PS (grouped) service has no exchanged information (as signal and data), releasing its occupied L2 (layer 2) connecting resource, and storing the relationship between relative L2 connecting mark and the L3 connecting mark; then, when the user of PS service has exchanged information, according to the stored relationship, building the L2 connection; therefore, user can via this L2 connection exchanges information or process PS service. The invention can release the L2 resource when there is no information exchange, and keep the user online, to save the system resource of RAN (wireless access network). Therefore, the invention can increase the number of online users.