Abstract：In order to clarify the blocking mechanism of skin on spherical bullet, a three-layer structural model of simulated skin was established. Based on the mechanical curves of tensile and compression experiments, the parameters of the skin model were identified by MATLAB. Based on the skin penetration threshold velocity obtained from the impact experiment, the accuracy of the skin model was verified. Then, the penetration process of Φ4.5 mm shot into the skin was simulated by LS-DYNA simulation, and the blocking effect of skin on spherical projectile was analyzed from the aspects of velocity attenuation and skin bulging. The penetration process of Φ4.5 mm projectile into the skin under the condition of the same kinetic energy and different density, together with the process of shot put into the skin with the same kinetic energy and different diameter, was numerically simulated. The results show that the three-layer structural model of skin can be taken as a numerical simulation model to simulate the real damage of skin. Furthermore, with the same initial kinetic energy, the smaller the density of spherical projectile is, the larger the volume is, the larger the energy dissipation ratio is, and the more obvious the skin blocking effect is. Such finding slay a foundation for the future study of the harm of the projectile to the real human body.