The gradient composite Whipple shielding structure was designed to improve the shielding capability of spacecraft. The hypervelocity impact of spherical projectile on the bumper of this shielding structure was numerically simulated by using ASYS/LS-DYNA hydro-code. The debris cloud formed by impacting this structure was compared with that of aluminum alloy Whipple bumper. The results show that the shielding effectiveness of the former is better than that of the latter under the condition of identical area density.