A method for a handover of a mobile station performed by a source base station and a target base station. The target base station receives a handover request message, from the source base station, in which includes QoS information of the mobile device, radio bearer identifier information of the source base station, and a first mapping relationship between a flow and a radio bearer of the source base station, the target base station acknowledges with a handover acknowledgement message. Therefore resource preparation at the target base station during a handover procedure is improved.