The stability and wave dissipation characteristics of breakwater reflect the important indicator of project quality and the function of the breakwater directly.The study of section stability，wave pressure and overtopping of Venezuela Puerto Cabello container terminal large-diameter cylinder breakwater under the effect of hundred years of random waves is based on the three-dimensional model test in wave basin.The test shows that the pressure on the forward direction of the cylinder is the highest;with the increase of water depth，the wave pressure shows a decreasing distribution;the maximum wave pressure of the wave wall appears in two-thirds of its height，and at this point，the wave pressure on the trim surface of the breakwater wave is the highest;at the junction of the parapet and the cylinder，because of the effect of overflow on both sides of the semi-circular parapet，the maximum wave pressure appears at both sides;and there is an overtopping phenomenon at the top of the parapet.The main causes of the wave height behind the breakwater are overtopping water and the wave which transmits through the cylinder.The wave trends stable after 150 m of the breakwater;the distance between the cylinders has little effect on the wave pressure on the cylinders wall，while the effect on the wave pressure on the parapet is much more obvious.