The objective of this research was to use experiments and simulations to evaluate the effect of different Kevlar thickness on the impact resistance.Three configurations were considered:(1)4mm base plate and 8.5mm Kevlar layer with 50mm air gap between layers;(2)the same steel plate and air gap before 14mm(consist of 8.5mm and 5.5mm)Kevlar layer; and(3)the same steel plate and air gap before 17mm(double of 8.5mm)Kevlar layer; In this paper,steel-cubic projectiles were fired at steel-kevlar plates from a distance of 15.0m.A 12.7 calibre gun was used to shoot 3.3g and 7.5g projectiles with velocities in the range of 1100-1300 m/s.Laser velocity screens were used to measure the input and output velocities.Nonlinear finite element(FE)simulations were developed to compared with experimental results and evaluate the response of Kevlar layer under different ballistic impacts.The effectiveness of different thickness of Kevlar layer in terms of ballistic resistances are presented and discussed.By comparing the reduction of the residual velocity,the relationship between the thickness of Kevlar layer and the capacity of kinetic energy absorption was established.Also,the characteristic of absorbing energy was obtained according to the damage region of Kevlar layer.These findings indicate that thicker Kevlar layer can be acted as protective device to reduce the energy of high velocity impact damage.