Abstract: Cylindrical breakwater is a new type of deep-water breakwater, which is proposed to be constructed on soft ground under severe wave loading. As it is not long before the trial section is built, no severe storm has been encountered till now. Therefore, a specific subject study on the cylindrical breakwater by centrifugal model tests is carried out to investigate the response of the cylindrical breakwater subject to the hypothesized wave load in the design. A specific in-flight simulator is developed to create the cyclic action of severe wave force at the appointed frequency. The response of cylindrical breakwater is depicted in terms of the horizontal, vertical and tilt displacements as well as the excess pore water pressure in the soft ground. The effect of height of lower cylinders and ballasting weight in upper cylinders are studied on working performance. Two main modes of failure are finally proposed in the design for the cylindrical breakwater, that is, the lateral translational sliding failure due to short height of lower cylinders and the overturning failure of excessive tilt displacement due to sustaining wave load with long duration.