The work aims to obtain the constitutive model parameters of the inner/outer shell material of the supercharged boiler in the marine power system equipment and analyze the penetration resistance of the structure under the impact of explosive fragments. The Modified Johnson-Cook (MJC) strength model parameters and Cockcroft-Latham (CL) fracture criterion parameters of outer shell material and inner shell material of the boiler were obtained through mechanical property test. By comparing the experimental results with the finite element simulation results, on the basis of verifying the validity of the material constitutive model, the penetration resistance of the inner/outer shell materials of the boiler was studied. The ballistic limits of fragment simulation projectile (FSP) penetrating into the outer shell and inner shell of the boiler were obtained. It was found that during the process of fragment simulation projectile penetrating vertically into the target plate of the inner/outer shell of the boiler, shear punching and ductile reaping occurred, and the bullet was abraded. Under high-speed impact, the 45° oblique penetration of the FSP was basically unaffected by the different contact sites at the initial penetration of the warhead, and the oblique penetration projectile had more serious abrasion. The constitutive model parameters can be used for the finite element numerical simulation of the impact and penetration resistance of the marine boiler, and the simulation results have a certain reference value for evaluating the damage of the marine power system under the fragment.