It is of great significance for the harbor layout and construction to master the wave height distribution characteristics in the harbor，while the physical modeling process is expensive and complicated.Most numerical simulations only consider the influence of waves propagating through the breakwater entrance and ignore the overtopping effect.To address these limitations，this paper establishes a three-dimensional numerical wave pool for a encircled vertical breakwater based on the open source software OpenFOAM，and compares the numerical calculation results in the case of overtopping and non-overtopping with the experimental results to verify the accuracy of the numerical model.The results show that the model can simulate the overtopping process at the top of the breakwater and the wave height distribution in the harbor well，and can be used for further research on the optimization of harbor layout.