The floating breakwater is mainly moored by chains or piles,et al.For the vertical pile-restrained floating breakwater,the motion of the floating body is mainly one degree freedom of heave.In this paper,the wave attenuation performance and wave force of the vertical pile-restrained single pontoon floating breakwater are studied by the 2D wave physical model tests.The study results show that the wave transmission coefficients of the vertical pile-restrained single pontoon floating breakwater increase with the relative width B/L decreasing under the same wave height.For the same relative width of the floating pontoon,the wave transmission coefficients of the vertical pile-restrained single pontoon floating breakwater are relatively small under relative large wave height,especially for conditions with large relative width (B/L＞0.2).Compared to the floating breakwater moored with chains,the wave transmission coefficients of the vertical pile-restrained floating breakwater are significantly reduced and the wave attenuation performance is significantly improved due to the fact that the wave reflection and wave energy damping are both significantly enhanced.Under wave action,the forward direction wave force of the vertical pile has a trend of decreasing with the relative width B/L decreasing (just the increasing of the wave period),and the opposite direction wave force has no significant varying trend with the relative width B/L varying.