The hypervelocity impact studied in numerical simulation way was discussed. Damage mechanism, the process of the debris cloud forming and its expanding were simulated with the SPH method of ANSYS/AUTODYN code when spherical projectile hypervelocity impacts thin shield. Tungsten alloy, RHA(Rolled Homogeneous Armor) and aluminum material models and parameters were given, using the modeling methods, material models and parameters of the numerical simulation results in good agreement with the experimental results. The debris cloud parameters such as Vx,max,Vy,max and the half-angle of maximum radial extension(θ₁) were obtained with numerical simulation, and the above parameters with the variation of the initial impact conditions were also studied. The empirical equations which relate these parameters to impact parameters, such as velocity, material parameters of projectile and target and plate thickness, were obtained based on dimensional analysis.