Abstract: One effect from an underwater explosion on ship hulls is the direct pressure, and the other is to create acceleration. Furthermore, the acceleration is not only created by ship hulls, but also by additional mass, which is also known as additional water mass, namely the explosion changes momentum and kinetic energy of ship hulls and additional mass at the same time.The research on a structure under an underwater explosion is very complex and has a huge quantity of calculation. For the purpose of selecting a composite hull structure, explosion loading is equivalent to static loading by means of an energy principle, the momentum principle and d’Alembert principle. According to the response of five different hull structures to equivalent loading, we select a hull structure. To the same molded lines of five different hull structure forms as longitudinal framing, transverse framing, a combined system, a hard-shell form and a sandwich form, the same loading and equal weight as a condition, the ship’s response created by an equivalent underwater explosion loading need to be analyzed by the finite element method. With the analysis of ship’s stress and displacement, we compare the strength, rigidity, section modulus and comprehensive performance of a ship to provide a numerical analysis reference for a structure selection. One structure form should be selected not only conforms to a structural performance, but also satisfies the use requirement.