Abstract: An approach combining the finite element method and the boundary element method is proposed in this paper to calculate the underwater vibration and acoustic radiation of a ring stiffened cylindrical shell under the reinforcement of various lateral plates. The effects of different lateral reinforced plates to the cylindrical shell are analyzed by comparing the respective numerical results. It is shown that lateral reinforced plates may reduce the vibration and acoustic radiation of the cylindrical shell，where the reduction effects are most significant on the plate build from longitudinal stiffeners，followed sequentially by stiffeners，semi-spacing boards and whole spacing boards. Also，the vibration and noise reduction becomes stronger as the frequency goes higher. It is worth noticing that the effects described in this paper are mainly restricted within the areas between the rings on the shell，and they are not so significant on low frequency vibration.