Embodiments provide a core network selection method, an apparatus, and a system. The method includes the following steps: obtaining first dedicated core network (DCN) information from an access network device, where the first DCN information includes information about at least one DCN that can be accessed by the access network device. The method also includes selecting a to-be-accessed DCN from the at least one DCN according to the first DCN information, and sending information about the to-be-accessed DCN to the access network device, so that the access network device determines a core network device according to the information about the to-be-accessed DCN.