Muzzle strong impact is a feasible test method of gun-power-recoil to simulate gun firing. For the firing simulation accuracy of gun-power-recoil test machine, a certain self-propelled gun was researched, and the virtual prototype model of gun-power-recoil test machine was built by using ADAMS/ATV. Based on the virtual prototype model, recoil displacement, recoil velocity, recoil acceleration curves were obtained. Through solving relative error of curves and landmark method, an evaluation method was presented which has two evaluating indexes, shape similarity and numerical value similarity. Simulation accuracy of the test machine was 0.8654, which indicated the test machine can simulate the dynamic characteristics of gun firing accurately.