Penetration structure with reinforcing rib can enhance compression and anti-bending capability of projectile, but it cant improve the stress concentration within the wall. The variable cross-section was analyzed and compared with cylindrical structure and reinforcing rib structure. The process of penetration into concrete target with actual speed was simulated by using AUTODYN-2D´a finite element software. The result shows that compared with the other two structures, the volume variation of projectile with variable cross-section is reduced and stress concentration during the process of penetration is improved, and the stability of projectile structure is effectively guaranteed so as to improve the security of internal charge of the projectile.