This application discloses a multicast forwarding method and a multicast router. The method includes: listening to, by a first multicast router, a plurality of unicast packets passing through the first multicast router, and determining a set of unicast packets that are from a same upstream multicast router and that belong to a same unicast stream; when determining that destination addresses of at least two unicast packets in the unicast packet set are different, sending, by the first multicast router, a prune message to the upstream multicast router; and sending, by the first multicast router, the received unicast packets with the multicast identifier to the destination devices corresponding to the destination address group. The method is used to provide a new multicast method, so as to implement multicast functions of some routers in an existing unicast network architecture.