Abstract: A numerical model used to simulate wave propagation was developed based on the Fluent software. Through simulating regular waves with different wave parameters, the relationships between the grid scale L/Δx and the quality of the simulated waves were analyzed. The grid scale for the numerical model was proposed according to the compared results, and the effectiveness of the damping absorber and the piston type wave making method were verified. On the basis of the numerical model, the focusing wave propagation was simulated by simulating wave spectrum. The simulated focusing wave time series and the water particle’s velocity under a focus point for 0.15 m were compared with the experimental results at different positions, and the effectiveness of the numerical model with the method for simulating wave spectrum was verified. Furthermore, the interaction between the focusing wave with a vertical cylinder was simulated. The numerical results including the focusing wave time series and water particle’s velocity time series under a focusing point for 0.15 m, the wave fluctuation time series around the cylinder, the point pressure time series on the cylinder and the cylinder’s positive total pressure time series were compared with the associated experimental results. The numerical simulation results were in good agreement with the experimental results. The comparison between the numerical and experimental results verified the effectiveness of the numerical model. At the end of this paper, in order to accumulate experience and lay a solid foundation for further research for interactions between the focusing wave and other forms of marine structures with the Fluent software’s platform, the error of the eigenvalues of the focusing wave height and the point pressure around the cylinder were calculated and causes of the error analyzed.