The present invention provides an intra-system handoff method, comprising the following steps: S302, when deciding a handoff of UE to a target base station, a source base station issues a handoff request to the target base station; S304, in response to the handoff request from the source base station, the target base station informs the source base station to conduct handoff for the UE; S306, after the completion of the handoff, the target base station issues an update request to an MME; and S308, in response to the update request from the target base station, the MME conducts Serving GW selection, and further fulfils the intra-system handoff. By the present invention, the target eNodeB need not determine whether access to the Serving GW is available, and accordingly the target eNodeB can avoid from configuring Serving GW.