Embodiments of this application provide a message forwarding method and an apparatus, so that a message for joining a multicast group is sent to a multicast user plane network element, and the multicast user plane network element is triggered to establish a tunnel for transmitting multicast data between the multicast user plane network element and an application server. The method may include: a multicast session management network element receives the message that indicates that a terminal is joining the multicast group; and when the terminal is the 1st terminal the multicast group, sends, to the multicast user plane network element, a message that requests to establish the tunnel for transmitting the multicast data between the multicast user plane network element and the application server.