A packet processing method includes determining, by a node in a first network, a transmission path for a packet, where the transmission path includes a path in the first network and a path traversing a second network; adding, by the node, path information to the packet based on the transmission path, where the path information includes traversal indication information, and the traversal indication information indicates an ingress node in the second network to encapsulate and transmit the packet based on an egress node that is specified in the traversal indication information and that is located in the second network; and sending, by the node to the ingress node in the second network through the first network, the packet to which the traversal indication information is added.