Embodiments of the present invention provide a method and device for determining a source SGSN. The method for determining a source SGSN comprises: obtaining addressing information of a source SGSN through an NAS message sent by a UE; sending the addressing information of the source SGSN to a target MME or a target SGSN, so that the target MME or the target SGSN can determine the source SGSN according to the addressing information of the source SGSN. The embodiments of the present invention can ensure that the MSC obtains the addressing information of the latest source SGSN of the UE, so that the target MME or the target SGSN obtains preparatory bearer information of the UE from the correct source SGSN.
