To improve the wave attenuation performance of floating breakwaters，an arc-wall-floating breakwater is proposed.Based on the theory of uncompressible fluids and VOF method，a two-dimensional numerical model is established by using the computational fluid mechanics software Star-ccm+，and the accuracy of the numerical model is verified.The numerical model is used to simulate and study the hydrodynamic properties of arc-wall-floating breakwaters under different horizontal widths，relative heights and relative wave heights.The influence of various parameters on the transmission coefficient，reflection coefficient and motion response of the breakwater is concluded，and the structural parameters of the breakwater with the best wave attenuation performance are identified.The results show that the transmission coefficient increases with the increase of the horizontal width，and the transmission coefficient can be stably maintained below 0.6 when the period is less than 1.4 s.The reflection coefficient decreases to a certain extent when the period is 1.6 s or 1.8 s.The motion response increases with the increase of horizontal widths and relative heights.