Abstract: In order to explore the rebound effect of projectile penetrating into concrete and reveal the mechanism, a basic theoretical hypothesis is put forward according to the mechanical model of the penetration-rebound process. The elastic deformation of the projectile is quantified based on the cavity expansion theory, and the rebound motion equation is established. The analytical solutions of displacement, velocity and acceleration in the rebound stage are obtained. It is studied that the technical means of numerical simulation to reproduce the rebound phenomenon of projectile. The rationality of the theoretical hypothesis is verified by the simulation results compared with the theoretical solution. The results show that the recovery of elastic deformation is the main reason for the rebound effect when the projectile penetrates the plain concrete target. The elastic deformation is related to the initial penetration velocity, the radius of the projectile, the mass of the projectile, the material density of the target plate and the shape coefficient of the projectile. The larger the aspect ratio of the projectile with the same mass, the more obvious the rebound effect.