Embodiments of the present invention disclose a communication method, a source base station, a target base station, a core network device, and a terminal device, where the method includes: sending, by a source base station, a handover request to a target base station, where the handover request is used to request to hand over a session of a terminal device from the source base station to the target base station, and the handover request includes an identifier of a session requested to be handed over and indication information of a network slice corresponding to the session; and receiving, by the source base station, a handover response message from the target base station, where the handover response message includes reject indication information, and the reject indication information is used to indicate cause information corresponding to a session, which is rejected by the target base station due to a network slice, from the session requested to be handed over. This application can increase a handover success rate.