In order to reduce workload for operation and maintenance of substation automation system and solve difficulties in checking signal of the new master station system， a new simulation system for substation automation is designed and implemented. The principles， architecture and construction features of the simulation system are described. The various module functions of the system and the ability of the simulation device are introduced in detail. With one PC， the simulation test system can exactly realize massive system simulation and different types of devices simulation based on virtual technology， and implement functions such as mass data testing， protection event simulation， global set action simulation， etc.