A multicast data packet processing method in a point-to-multipoint (P2MP)-based bit index explicit replication (BIER) multicast tree, which includes an intermediate node configured to use P2MP to forward a BIER packet, includes receiving a first multicast data packet with a BIER header having a first label. The method further includes obtaining a first forwarding entry based on the first label. The first forwarding entry includes the first label, a first identifier identifying the multicast tree, and a second identifier instructing to perform P2MP forwarding. The method further includes obtaining, based on the first identifier, a second forwarding entry including the first identifier and a second label. The method further includes obtaining a second multicast data packet based on the second identifier, the second forwarding entry, and the first multicast data packet, and sending the second multicast data packet. The second multicast data packet includes the second label.