In order to suppress the impact of liquid in the large Liquefied Petroleum Gas (LPG) storage tanks of Floating Production Storage and Offloading (FPSO) on the hull, the wave-breaking plates are be used. The Computational Fluid Dynamics (CFD) software is used to analyze the sloshing suppression features of the wave-breaking plates and the stress calculation is carried out. The Volume of Fluid (VOF) gas-liquid two-phase model is used to establish the mixed mesh generation model of hexahedron and tetrahedron. The ship sloshing is simulated by the dynamic grid function of CFD. The results show that the accuracy of the numerical model is verified by the comparison with experimental data. The numerical simulation results show that the wave-breaking plates could effectively suppress the movement of the liquid, stabilize the pressure distribution and fluctuation, reduce the impact of liquid on the tank, and thus ensure the safe application of the large LPG tanks on FPSO.