Method, device and system for selecting gateway when switching in heterogeneous network

Embodiments of the present invention disclose a gateway selection method for heterogeneous networks, where the method includes: accessing, by a terminal, an access network 1; obtaining, by the terminal, an equipment identity of a core network element 1; accessing, by the terminal, an access network 2, where the access network 2 and the access network 1 are heterogeneous networks; and sending, by the terminal, the obtained equipment identity of the core network element 1 to a core network element 2, and if an equipment identity of the core network element 2 is different from the equipment identity of the core network element 1, selecting the core network element 1 as a target gateway. Accordingly, the embodiments of the present invention further provide a terminal, a core network element, and a communication system.