Abstract: Due to the high penetration-resistance of thick ultra-high molecular weight polyethylene fiber reinforced plastic(UFRP)laminates under high velocities,the whole penetration process is divided into three phases:cratering & mushrooming phase,shearing & compression phase,and stretching deformation phase. By altering the computation method for the cratering & mush rooming phase and the calculation process for the stretching deformation phase,an analytical model is established based on the energy conservation principle to compute the penetration depth of projectiles as well as the ballistic limits of laminates in the case of thick UFRP laminates being penetrated by high-velocity blunt-nosed projectiles. The corresponding computation flow charts are also presented. Moreover,penetration depths of projectiles and ballistic limits of thick laminates under different test conditions are calculated with the model in a correlative order. It is seen that good agreements are obtained between the theoretically values and experimental results. Therefore,the improved model,which considers the projectile initial velocity effects on penetration depth during the cratering & mushrooming phase,can be employed to reasonably predict the penetration depths and can reduce experimental costs,demonstrating both theoretical and engineering values.