Aiming at the challenges brought by time-varying topology structure of space-based networks to network management and routing design

considering the advantages of GEO satellites and LEO satellites

a space-based network model based on SDN architecture is established

a virtual topology-based approach is proposed. A spacebased network routing algorithm which contains required node that must pass through the nodes

（ VTPN） is proposed. By improving the time slice division strategy

the computational efficiency is improved

and the link congestion problem is improved by setting of passing through node. The simulation results show that compared with other algorithms

the VTPN algorithm under the SDN architecture improves the network link utilization and load balancing performance by about 50 %

and the packet loss rate decreases by about 20%.