A joint route query method in ASON. After the route controller in each route domain has received a route query request, it calls a routing algorithm based on the request and the route calculation is performed based on the route database of the current node; if the route calculation succeeds, a route query result is returned to the requester, if no complete route can be obtained, said route query request will be forwarded to the RC in the parent domain. Based on the request, the RC in the parent domain interacts with RCs in other domain of the same layer, and the RCs in the sub-domains contained in the parent domain to complete the route query, and calculates to obtain a complete route, then a route query result will be returned to the RC that initiates the request and this RC will return the route query result to the requester.