A physical model test method is carried out to study the wave dissipation performance of the trapezoidal and rectangular combined submerged breakwaters.The attenuation effect of the single submerged breakwater and the combined ones is compared,and the effect of some factors such as the water depth on the breakwater,the wave height,the spacing and the number of submerged breakwater on the transmission coefficient Kt of submerged breakwaters are analyzed.The experimental results show that the transmission coefficient of the combination of submerged breakwaters increases with the water depth on the breakwater,and decreases with the increase of wave height.When the distance between the combined submerged breakwaters is close to half wave length,the wave dissipation effect is comparatively obvious.The more breakwaters submerged in the water,the better the attenuation effect achieved,and the number can be chosen according to the actual project.