Method, device and system for selecting packet data network gateway (PDN GW) node

The embodiment of the invention discloses a method, device and system for selecting a packet data network gateway (PDN GW) node. The method comprises the following steps: network equipment receives an attachment request message from user equipment (UE), the attachment request message carries the mobile station network capability information of the UE, and the mobile station network capability information of the UE comprises the client mobile internet protocol (CMIP) capability information of the UE; and the network equipment selects the PDN GW node for the UE according to the CMIP capability information of the UE. Through the embodiment of the invention, when the UE is switched from a 3GPP (the 3rd Generation Partnership Project) access network to a non-3GPP access network, the continuity of service can be realized.