This paper generates a three dimensional random aggregate model with the dual relationship between Delaunay triangulation graph and Voronoi diagram. The Delaunay triangulation algorithm in 2-D is spread to 3-D with programming language and ANSYS. In order to verify the effectiveness of the proposed model and analysis method, the existing penetration experiments of concrete slabs are numerically simulated and analyzed by employing the hydrocode LS-DYNA. Finally, numerical simulation of the projectile penetration into the concrete slabs is presented to study the effect of the diameter of aggregate and the volume percentage on the yawing angle and residual velocity of the projectile. It is indicated that the ratio of aggregate average diameter to the projectile diameter has more obvious effects on yawing angle than volume percentage. When the ratio reaches a certain value, the yawing angle is constant. In addition, the residual velocity of projectile decreases with the increase of the diameter and volume percentage of aggregate.