A core network device selection method and apparatus are disclosed. The method includes: receiving, by an access network node, an access stratum message sent by a terminal, where the access stratum message includes a NAS request message and a network selection auxiliary parameter; querying configuration information based on the network selection auxiliary parameter, and determining a group identifier of at least one mobility management device group, where the configuration information includes a correspondence between a network selection auxiliary parameter and a group identifier of a mobility management device group; determining a device identifier of a target mobility management device based on the group identifier of the at least one mobility management device group; and sending the NAS request message to a mobility management device indicated by the device identifier of the target mobility management device.