Abstract: By changing the jacket, the filler and the impact velocity of the PELE projectiles, the impact behaviors of the PELE projectiles perpendicularly perforating thin target plates were investigated experimentally. On the basis of the experimental results, the stresses of the PELE projectiles during their penetration into the targets were analyzed and the lateral effect production mechanism was illuminated. On some hypotheses, the theoretic models were established for the residual and radial velocities of PELE projectiles penetration into thin targets. The calculated results by the established models are in approximate agreement with the experimental results. The theoretical and experimental investigations show that the ratio of the compressive-to-tensile strength of the jacket, the Poissons ratio and elastic modulus of the filling material, and the impact speed of the PELE projectile affect the lateral effect markedly.