Abstract: The current practice of the surge protection device (SPD) is when the electrical overload occurs, the voltage pulse signal exceeds the maximum rate of the system, the shunt element with nonlinear voltage-current (V-I) characteristics show minimal impedance in the over voltage state, whereas in the normal case it show high impedance. The method is based on surge current/ voltage waveform parameter and achieves the ultimate protection purpose through multilevel coordination protection. Defense system is introduced in this paper for the power electronic equipment with UPS backup power supply, the system is based on the characteristics of continuous current pulse in the development process of lightning leader, the microsecond switch cut off the protected equipment from the outside before the lightning strikes the ground, forming an ‘island’ to achieve the purpose of protection, in 1- 2 seconds. After the end of the lightning process, the external power supply will be restored, to significant reduce the correlation between protection design, device, and surge voltage/current waveform parameters. In addition, the system only needs first level protection, which can reduce the difficulty of current lightning multi-stage protection design, thus achieving the purpose of improving the protection effect.