Abstract: The dynamic mechanical behavior of a metallic hierarchical corrugated sandwich beam with a hierarchical design under foam projectile impact was studied. After verifying the reliability of the numerical method, the dynamic deformation evolution, quantitative deflection results, deformation failure modes, and energy absorption characteristics of the metallic hierarchical corrugated sandwich beam were analyzed using Abaqus-Explicit simulation results under different projectile momentum levels. The results show that the degree of crushing of the secondary corrugated core on the impact side and the first-order corrugated core of the hierarchical sandwich beam is always greater than that of the rear sandwich's secondary corrugated core. The final mid-span deflection of the rear face of the hierarchical corrugated sandwich beam is always smaller than the corresponding deflection value of the equivalent mass single-level empty corrugated sandwich beam, demonstrating the superior impact protection performance of the hierarchical sandwich beam. This enhancement mechanism is mainly attributed to the increased energy absorption of the added cellular cores, which protects the rear face sheet. Besides, the plastic longitudinal stretching strength of the hierarchical sandwich beam remains almost unchanged, while the plastic bending strength increases due to the increase in the total thickness of the beam structure, thereby enlarging the plastic yield surface of the sandwich structure.