In this paper,the penetration behaviors of 4.6 mm thickness armor steel under different projectile velocities of type 537.62 mm common steel core bullet were studied by computer simulation analysis.The anti-ballistic performance parameters(including back projection height and crater depth) of the target plate under different projectile speeds was calculate by regression analysis with the least square method.Furthermore,a mathematical model between anti-ballistic performance parameters and projectile speed was constructed.And then,combined with the back projection height and crater depth when the target plate was shot through,the ultimate resistance velocity of the target was predicted.During simulation,the simplified J-C constitutive model was selected to set the material parameters of the target plate ignoring influence of temperature.The corresponding model parameters were calculated from the quasi-static and dynamic compressive stress-strain curves.In order to ensure the accuracy of the prediction model,the anti-ballistic performance of target plate was tested at different shooting distances.Thereby the prediction model was modified by using the actual measured results.The results show that,the simulation results are in good agreement with actual shooting results,and the simulation accuracy of crater depth and back projection height reach to 86.5% and 88.2%,respectively.This thin armor steel shows excellent anti-ballistic performance,and the ultimate velocity of its impact failure is estimated to be about 1000 m/s.Within the velocity range of the projectile,the back projection height(H) and crater depth(D) of target plate are approximately linear to the projectile velocity(v) and the square velocity(v2),which could be expressed as H=-9.575+0.01644v,H=-3.213+1.05988 10-5v2,D=-13.425+0.02372v and D=-4.247+1.52939 10-5v2 after modification,and the prediction accuracy of all the modified models are above 92%.