Aiming at the impact of waves passing over submerged breakwater on the wave height behind the breakwater,the physical model experiment method is employed to investigate the effects of relative submergence depth,relative crest width,slope gradients of the front and back slopes,and wave steepness on the transmission coefficient of the submerged breakwater under irregular wave action.Based on the experimental data,a formula for calculating the transmission coefficient of submerged breakwater under irregular wave conditions is fitted.The results show that the transmission coefficient decreases with increasing relative submergence depth,relative crest width,or wave steepness.When the slope gradients are within the range of 1:1.0 to 1:2.5,the front and back slope gradients have almost no effect on the transmission coefficient of the submerged breakwater.A comparison between the fitted formula and commonly used empirical formulas shows that the fitted formula can calculate the transmission coefficient of submerged breakwater well.