A handover method, comprising: receiving, by a mobility management network element of a first network, a first handover request sent by an access network of the first network, and learning that a terminal device needs to be handed over to a second network; obtaining, by the mobility management network element of the first network, an identifier of the terminal device based on the first handover request; determining, by the mobility management network element of the first network, a target mobility management network element of the second network based on the identifier of the terminal device; and sending, by the mobility management network element of the first network, a second handover request to the target mobility management network element of the second network, and requesting to hand over the terminal device to the second network; wherein the determining, by the mobility management network element of the first network, a target mobility management network element of the second network based on the identifier of the terminal device comprises: obtaining, by the mobility management network element of the first network, a usage type of the terminal device from a subscription database based on the identifier of the terminal device; and determining, by the mobility management network element of the first network, the target mobility management network element of the second network based on the usage type of the terminal device; or wherein the determining, by the mobility management network element of the first network, a target mobility management network element of the second network based on the identifier of the terminal device further comprises: obtaining, by the mobility management network element of the first network, a target core network identifier of the second network based on the identifier of the terminal device; and determining, by the mobility management network element of the first network, the target mobility management network element of the second network based on the target core network identifier of the second network. receiving, by a mobility management network element of a first network, a first handover request sent by an access network of the first network, and learning that a terminal device needs to be handed over to a second network; obtaining, by the mobility management network element of the first network, an identifier of the terminal device based on the first handover request; determining, by the mobility management network element of the first network, a target mobility management network element of the second network based on the identifier of the terminal device; and sending, by the mobility management network element of the first network, a second handover request to the target mobility management network element of the second network, and requesting to hand over the terminal device to the second network; wherein the determining, by the mobility management network element of the first network, a target mobility management network element of the second network based on the identifier of the terminal device comprises: obtaining, by the mobility management network element of the first network, a usage type of the terminal device from a subscription database based on the identifier of the terminal device; and determining, by the mobility management network element of the first network, the target mobility management network element of the second network based on the usage type of the terminal device; or wherein the determining, by the mobility management network element of the first network, a target mobility management network element of the second network based on the identifier of the terminal device further comprises: obtaining, by the mobility management network element of the first network, a target core network identifier of the second network based on the identifier of the terminal device; and determining, by the mobility management network element of the first network, the target mobility management network element of the second network based on the target core network identifier of the second network. obtaining, by the mobility management network element of the first network, a usage type of the terminal device from a subscription database based on the identifier of the terminal device; and determining, by the mobility management network element of the first network, the target mobility management network element of the second network based on the usage type of the terminal device; or wherein the determining, by the mobility management network element of the first network, a target mobility management network element of the second network based on the identifier of the terminal device further comprises: obtaining, by the mobility management network element of the first network, a target core network identifier of the second network based on the identifier of the terminal device; and determining, by the mobility management network element of the first network, the target mobility management network element of the second network based on the target core network identifier of the second network. obtaining, by the mobility management network element of the first network, a target core network identifier of the second network based on the identifier of the terminal device; and determining, by the mobility management network element of the first network, the target mobility management network element of the second network based on the target core network identifier of the second network.