To verify the wave dissipation effect of a new type of low-permeability breakwater with pile foundations，this paper carries out model prediction and evaluation after on-site wave observation. The relative wave height of the internal and the external areas，which can reflect the wave dissipation effect of the breakwater，is obtained by the sectional model test，the whole model test and the post-observation of wave data on both sides of the breakwater. The results show that in the conditions of water depth＞10 m，H1/10＞2.5 m and nearly 180° open sea area，the structure is able to meet the requirement that the relative wave height is controlled within 0.3. In the actual sea conditions，the relative wave height has a significant relationship with the external wave steepness and the tide level. Generally，the wave steepness is larger and the relative wave height is smaller when the tide level is lower.