Embodiments of this application disclose a method for discovering a forwarding path and a related device thereof, to discover a forwarding path. The method includes: receiving, by a first device, a packet that is sent by a second device and that is used to discover a forwarding path; searching, by the first device based on a first forwarding entry of a data plane, for forwarding information used to forward the packet; and sending, by the first device, path information to the second device based on a second forwarding entry of an autonomic control plane virtual routing and forwarding (ACP VRF) instance, where the first forwarding entry and the second forwarding entry are isolated from each other. In the embodiments, the first forwarding entry and the second forwarding entry are isolated from each other, and returning of the path information is not affected by a data plane fault.