This paper explains that refraction reflection coefficients will change at different time when the lightning wave comes,as a result,the shape of lightning wave will change when they get through the series inductance.Voltage amplitude of lightning wave will reduce as long as the gradient of lightning wave decreases.According to this basic principle,a large scale of tests were carried out on ICGS.Comparative analysis shows that the residual voltage could be reduced by adding of the series inductance,thus enhance the tolerance capacity and improve the protection effect of multi-stage SPD.The application of series inductance in SPD is of great significance to the lightning protection in the power distribution system.