A method for updating identity information of a packet gateway, an authentication, authorization, and accounting (AAA) server and a packet gateway. The method includes: a decision-making network element receiving a message which carries user equipment (UE) capability indication information and is sent by an information transmission network element; the decision-making network element deciding whether to update identity information of the packet gateway or not according to the UE capability indication information carried in the message and/or local information. The technical solution can be applied to distinguish R11 UE and R12 UE, and to ensure supporting both the R11 UE and the R12 UE normally accessing to a 3GPP core network through a 3GPP access system and a non-3GPP access system simultaneously.