A registration method, a session establishment method, a terminal, and an access and mobility management function (AMF) entity, where the method includes sending, by a terminal, a first message to the AMF entity, where the first message includes first information, first network slice selection information, and second network slice selection information, the first information includes information for requesting to establish a protocol data unit (PDU) session, the first network slice selection information is used by the AMF entity to select a first session management control function (SMF) entity, and the second network slice selection information is used by the AMF entity to select a second SMF entity, and receiving, by the terminal, a second message from the AMF entity, where the second message includes second information, and the second information includes PDU session establishment accept information.