In the field of communications, a method, a system, and a device for implementing service forwarding are disclosed. The method includes: establishing an optical network tunnel between data communication devices; triggering physical interfaces of the data communication devices directly connected to an optical network to start a link layer protocol after the optical network tunnel is successfully established; performing, by the data communication devices, link layer negotiation through the optical network tunnel according to the link layer protocol; setting a link layer state between the data communication devices and a physical state of the physical interfaces to be valid after the link layer negotiation is performed successfully; and implementing, service forwarding, by the data communication devices through the optical network tunnel after the link layer state and the physical state of the physical interfaces are set to be valid. In this way, Internet Protocol (IP) / Multi-Protocol Label Switching (MPLS) service forwarding of the data communication devices is implemented, implementation complexity of bearing the IP / MPLS service over a Generalized Multi-Protocol Label Switching User-Network Interface (GMPLS UNI) tunnel is reduced, reconstruction on an IP / MPLS control plane and a forwarding plane is decreased, and forwarding performance is improved.