The purpose of this paper was to study the damage mechanism of the underwater contact explosion test of the model structure, which provided a basis for the protection mechanism of the side protective structure. This paper adopted an energy principle method to analyze and study the damage mechanism of underwater contact explosion test of ship protection structure model, and then used the software for numerical calculation. The dynamic curves of stress, strain and displacement of typical parts of the ship protection structure model were obtained. After comparing the experimental data, the numerical results were reasonable and credible.