In view of the existence of vortex-induced vibration,poor structural stability and obvious dynamic characteristics of the high fineness ratio floating structures under water,the mechanical characteristics and dynamic characteristics of the floating structure under water are analyzed and calculated,so as to find a way to reduce the vortex-induced vibration effect of the floating structure under water.At the same time,physical model test is used to verify the accuracy of the research results.The results show that the vortex-induced vibration of underwater floating structures can be effectively reduced by using reasonable baffle structure.The theoretical analysis and simulation method can be effectively applied to the underwater floating structure optimization design.