In the invention, PSPICE simulation software and a combination wave are used to test a residual voltage and a through-flow amount of a multistage surge protector SPD under line-ground and line-line work modes. Simultaneously, an actual impact test platform is used to carry out an actual impact test of a multistage SPD, and then a simulation test result is compared to an actual impact test result. And a final acquired maximum residual pressure value and a maximum through-flow capacity of a simulation test are more ideal than those of actual measurement. In the invention, the actual impact test result is used to verify a simulation result so that feasibility of a PSPICE simulation impact test is fully explained; the simulation impact test can be used as a replacement of the actual impact test or be used to compare verification data; and a reference basis is provided for a SPD application.