Abstract: The propagation of shock wave in Al/Mg wave impedance-grade material target is studied by numerical simulations. The duration of the shock wave in the target, the plastic work and the internal energy converted from the kinetic energy of the projectile are obtained. It is indicated that the integrals of the pressure over time in the wave impedance-grade material target are increased by 30%～50% as compared with those in the aluminum alloy target at the velocity range of 3.0～7.0 km/s. Meanwhile, the plastic work and the internal energy rise by 10% when the aluminum target is replaced by the Al/Mg wave impedance-grade material target under the same impact conditions. All results support the conclusion that the wave impedance-grade target performs better than the aluminum alloy target in protection against hypervelocity projectiles.