Abstract: In this paper, the kinetic equilibrium equations for discrete fluid and structure are derived by structural finite element method and fluid finite element method on the basis of Galerkin method and Hamilton抯 Principle. The added mass matrix for fuild is obtained by wet modal method. A modal analysis is conducted on fluid structure interaction system of bulkhead stiffened plate of high-speed ship. In order to study the modal characteristics for different depth of water, a modal experiment is done. The experimental result is compared with that of finite element analysis. The present work may offer guidelines on the dynamical design of bulkhead stiffened plate of high-speed ship.