According to the problem that the current smart substation simulation system can not be well applied in transformer substation, a novel integrated testing method is proposed for secondary equipment based on wireless data communication, and the hardware and software of testing system are developed also. In this system, electromagnetic transient calculation is adopted to get the current and voltage value of substation normal running or malfunction, which is transferred to the tested substation interval by special submillisecond wireless channel, and some distributed terminals are designed to realize the seamless connection between the simulation system and substation secondary system. This system can realize the integrated testing of different functions of secondary system in smart substation, and the effectiveness of the testing system is proved by substation model founding and fault simulation.