A bearer establishment method comprising: receiving, by a mobility management entity, a first request message from an access network device, wherein the first request message is received from a source access network device or a target access network device in a cell handover process of a terminal; determining, by the mobility management entity, a target serving gateway of the terminal and a target packet data network gateway of the terminal based on the first request message; sending, by the mobility management entity, a second request message to the target serving gateway, wherein the second request message is used to request the target serving gateway to establish a first bearer for the terminal, and the first bearer is a bearer between the target serving gateway and the target packet data network gateway; receiving, by the mobility management entity, a second response message from the target serving gateway, wherein the second response message carries an IP address assigned by the target packet data network gateway to the terminal; and sending, by the mobility management entity, the IP address to the terminal, wherein the first request message carries an identifier of a target cell of the terminal, and the determining, by the mobility management entity, a target serving gateway of the terminal and a target packet data network gateway of the terminal based on the first request message comprises: obtaining, by the mobility management entity, the identifier of the target cell from the first request message; and determining, by the mobility management entity, the target serving gateway of the terminal and the target packet data network gateway of the terminal based on the identifier of the target cell. receiving, by a mobility management entity, a first request message from an access network device, wherein the first request message is received from a source access network device or a target access network device in a cell handover process of a terminal; determining, by the mobility management entity, a target serving gateway of the terminal and a target packet data network gateway of the terminal based on the first request message; sending, by the mobility management entity, a second request message to the target serving gateway, wherein the second request message is used to request the target serving gateway to establish a first bearer for the terminal, and the first bearer is a bearer between the target serving gateway and the target packet data network gateway; receiving, by the mobility management entity, a second response message from the target serving gateway, wherein the second response message carries an IP address assigned by the target packet data network gateway to the terminal; and sending, by the mobility management entity, the IP address to the terminal, wherein the first request message carries an identifier of a target cell of the terminal, and the determining, by the mobility management entity, a target serving gateway of the terminal and a target packet data network gateway of the terminal based on the first request message comprises: obtaining, by the mobility management entity, the identifier of the target cell from the first request message; and determining, by the mobility management entity, the target serving gateway of the terminal and the target packet data network gateway of the terminal based on the identifier of the target cell. obtaining, by the mobility management entity, the identifier of the target cell from the first request message; and determining, by the mobility management entity, the target serving gateway of the terminal and the target packet data network gateway of the terminal based on the identifier of the target cell.