Abstract: Aiming at the issue of projectile penetrating concrete structures, a novel decoupling algorithm for penetration resistance is proposed. This algorithm ensures computational accuracy while overcoming the inefficiencies of explicit dynamic software. Based on the compressible elastic-crack-crush zone model for both plain and reinforced concrete, the algorithm decouples penetration resistance from the concrete structures, and applies it as radial stress normal to the projectile's contact surface. Program design is carried out in the explicit dynamic software LS-DYNA and ABAQUS. By assigning material parameters and initial conditions, the motion state of the projectile can be calculated, resulting in a stable and efficient decoupling algorithm for penetration resistance. The results demonstrate that the algorithm's computational predictions closely match experimental data. Compared with the finite element method, the decoupling algorithm exhibits significant advantages in computational stability and efficiency. It shows low sensitivity to mesh size, achieving high accuracy and speed when the ratio of mesh size to projectile diameter ranges from 0.066 to 0.131. This decoupling algorithm offers engineers and researchers a convenient and practical method for predicting projectile penetration effects, providing a rapid assessment tool for evaluating the anti-penetration performance of concrete structures.