This application provides a network establishing method, an Ethernet system, and a vehicle. A network includes M backbone nodes. Each of the M backbone nodes includes a first backbone port and a second backbone port. The M backbone nodes form a ring network by using the first backbone ports and the second backbone ports. M is an integer greater than 2. The M backbone nodes include a first backbone node. The first backbone port of the first backbone node is in a forwarding state, and the second backbone port of the first backbone node is in a blocked state. Both the first backbone port and the second backbone port of another backbone node are in a forwarding state.