In this study, sloshing analyst and optimum ring baffle design are studied. Sloshing in axisymmetric tank of arbitrary shape `is modeled by spring-mass-damper model. Sloshing analysis results for tanks in various shape are verified by comparing the results with those obtained from references and commercial code(MSC/NASTRAN). Optimum ring baffle design is also studied. An algorithm is developed with which optimum ring baffle locations and width can be obtained. In this algorithm, the lateral force for a given lateral acceleration history is minimized.