The embodiments of the present invention relate to the field of computer networks, and disclose a method and an apparatus for processing a multicast packet. The method includes receiving a multicast packet (101), acquiring a local router interface corresponding to the multicast packet according to a multicast routing entry carried in the multicast packet (102), and forwarding the multicast packet through the acquired local router interface to a clustered routing system interface for further transfer (103). The embodiments of the present invention can cluster several routing devices into a virtual routing system which externally acts as a single routing node for supporting a multicast service, so as to implement the efficient and reliable forwarding of the multicast packet in a clustered routing system with virtual aggregation, and enable the clustered routing system to support the multicast service with high efficiency and quality.