A session management method, comprising: receiving (402, 502, 702), by a first session management network element, a request message from a second session management network element, wherein the request message requests to establish a new branch of a session, the session comprises an established branch corresponding to a first anchor user plane function network element managed by the second session management network element; selecting (503, 703), by the first session management network element, a second anchor user plane function network element for the new branch of the session; sending (504, 704), by the first session management network element, a session establishment request message to the second anchor user plane function network element; receiving (504, 704), by the first session management network element, a session establishment response message from the second anchor user plane function network element; selecting (505, 705), by the first session management network element, a branching point user plane function network element, wherein the branching point user plane function network element is connected to an access network element, the first anchor user plane function network element, and the second anchor user plane function network element; sending (506, 706), by the first session management network element, a session establishment request message to the branching point user plane function network element; receiving (506, 706), by the first session management network element, a session establishment response message from the branching point user plane function network element; allocating (403, 507, 707), by the first session management network element, internet protocol, IP, information of a terminal device to the new branch of the session based on the second anchor user plane function network element; and sending (404, 508, 708), by the first session management network element, a response message to the second session management network element, wherein the response message comprises the IP information of the terminal device. receiving (402, 502, 702), by a first session management network element, a request message from a second session management network element, wherein the request message requests to establish a new branch of a session, the session comprises an established branch corresponding to a first anchor user plane function network element managed by the second session management network element; selecting (503, 703), by the first session management network element, a second anchor user plane function network element for the new branch of the session; sending (504, 704), by the first session management network element, a session establishment request message to the second anchor user plane function network element; receiving (504, 704), by the first session management network element, a session establishment response message from the second anchor user plane function network element; selecting (505, 705), by the first session management network element, a branching point user plane function network element, wherein the branching point user plane function network element is connected to an access network element, the first anchor user plane function network element, and the second anchor user plane function network element; sending (506, 706), by the first session management network element, a session establishment request message to the branching point user plane function network element; receiving (506, 706), by the first session management network element, a session establishment response message from the branching point user plane function network element; allocating (403, 507, 707), by the first session management network element, internet protocol, IP, information of a terminal device to the new branch of the session based on the second anchor user plane function network element; and sending (404, 508, 708), by the first session management network element, a response message to the second session management network element, wherein the response message comprises the IP information of the terminal device.