A method, an apparatus, and a system for updating packet data network gateway (PDN GW) information are disclosed. The method includes: receiving, by a home subscriber server (HSS), an update request sent by a first network element (NE), where the update request includes a Context-Identifier parameter and an international mobile subscriber identity (IMSI); and updating PDN GW information according to the Context-Identifier parameter and the IMSI. With embodiments of the present invention, the data matching speed is increased in the update process, and the performance of the HSS is improved.