Abstract: Composite bucket foundation breakwater is a new structure applicable for soft clay and large wave load conditions. A series of centrifuge tests are conducted to study the failure modes and bearing capacity of the structure as well as the effects of undrained strength of soils and load eccentricity. Main conclusions are as follows: the load-displacement curves for rotation angle, horizontal displacement and vertical displacement can be divided into elastic displacement stage and failure stage, except when the undrained strength of soils is 44.5 kPa, the failure stage of vertical displacement does not appear. With the increase of moment load, the rotation center moves downward below seabed level, and as the moment load reaches bearing capacity, the rotation center is located at bucket tip. When the undrained strength of soils and load eccentricity is low, the structure has a rotational and vertical displacement mode. As the load eccentricity increases to 10.5 m and 13.5 m, the displacement mode converts to a combination of rotational, horizontal and vertical displacements. As the undrained strength of soils increases to 44.5 kPa, the displacement mode converts to a combination of rotational and horizontal displacements. Under the same undrained strength of soils, the bearing capacity of the moment decreases linearly with the increase of the bearing capacity of horizontal load. Under the same load eccentricity, the bearing capacity of the moment increases linearly with the increase of the bearing capacity of horizontal load. The results reveal the failure mode and bearing capacity of the composite bucket foundation breakwater, and provides reference for the optimal design of the structure.