1. An inter-domain virtual network mapping method, comprising: receiving an inter-domain virtual network request; obtaining a latest physical network architecture information of each of N network domains; calculating an optimized mapping solution according to the latest physical network architecture information of the N network domains to divide an inter-domain virtual network into N virtual sub-networks, each virtual sub-network corresponding to one of the N network domains; sending each virtual sub-network to a corresponding network domain thereof and performing a mapping in each network domain; initializing SUM=0, and updating SUM according to a result of the mapping in each network domain; determining whether SUM is equal to N; if yes, instructing each network domain to distribute a physical network source for the inter-domain virtual network request; and if no, instructing each network domain to undo any procedure.