Experimental method, finite element simulations and theoretical analysis were developed in this paper to study the impact resistance performance of metallic sandwich panels under low velocity impact. First, the dynamic performance and damage situation of metallic sandwich panels under drop hammer impact were analysis. Finite element method was also used to simulate the experiment, and the applicability of finite element analysis was verified. Then, the total potential energy was established by local deformation potential energy and external force work. The relationship between the concentrated force and local deformation was also obtained. The cracking impact force of the sandwich panels was obtained for the tensile fracture of the face sheets as the failure condition. Finally, the finite element models were established to calculate the cracking impact force of the panels, and the results were compared between the finite element method and the formula calculation. It shows that, the cracking impact force of the panels was increased with the strength and thickness of the face sheets, hammer radius and cracking strain, with independency of the hammer mass, strength and thickness of the core.