The present application discloses a method for supporting a selected IP traffic offload (SIPTO) by a mobility management entity (MME) when a user equipment (UE) handovers from a source base station to a target base station in a mobile communication system. The method includes acquiring a local home network identifier (ID) of the source base station, acquiring a local home network ID of the target base station from the target base station, and determining whether the UE has moved out of the local home network of the source base station according to the local home network ID of the source base station and the local home network ID of the target base station.