In this paper，a re1iable and effective method for calculating the dynamic characteristics of fluid-filled cylindrical tanks is developed. And the effect of the coupling between liquid sloshing and shell vibration is considered. The liquid is assumed to follow the velocity potential theory，and the shell is modeled by the finite element method. In this approach，the number of unknowns is substantially less than those in analyses where both tank wall and liouid are subdivided into finite elements.