A G.709 based multiplexing routing control method and gateway network element. The method includes carrying, in a gateway network element, the multi-stages multiplexing capability of the gateway network element in a link state broadcast data packet, and broadcasting, through a routing protocol, the multi-stages multiplexing capability of the gateway network element to the routing area or Path Computation Entity (PCE) in which the gateway network element is located. The gateway network element is configured to carry the multi-stages multiplexing capability of the gateway network element in a link state broadcast data packet, and to broadcast, through a routing protocol, the multi-stages multiplexing capability of the gateway network element to the routing area or PCE in which the gateway network element is located. This enables the multi-stages multiplexing capability of the gateway network element to be broadcasted to other network elements, resolving interconnection and intercommunication problems between new and old equipment.