Based on the concept of DiffServ (Differentiated Service), an on-board switch framework is proposed, which satisfies QoS performance requirements and maintains a fairly low complexity. It applies the (m, k) model to the mapping between the terrestrial and satellite network traffic and uses the double-LB (Leak Bucket) model to control the traffic efficiently. Simulation results show that the scheme significantly improves the QoS performance, smoothes the burst traffic and saves the on-board buffer reservation.