A test scheme based on digital dynamic real time simulation technology for the secondary automation devices in digital substation is proposed. The testing system has static and dynamic testing functions. By setting-up the models of primary system， the high accurate simulation of electromagnetic transients for power grid is processed. The simulation results are sent to the real digital relays according to IEC 61850 protocol. The system not only can carry the routine tests for single device， but also can complete integrated closed loop tests for all of the secondary automatic devices in the digital substations.