A method for sending a multicast packet provided in embodiments of this application includes: a first network device obtains a first multicast packet, where the first multicast packet includes a bit string bit string and an identifier of a network slice, the bit string corresponds to a second network device, and the network slice corresponds to a multicast service of the second network device. The first network device obtains, based on the bit string and the identifier of the network slice, a first interface corresponding to the network slice. The first network device sends the first multicast packet to the second network device by using the first interface.