Abstract: By improving the existing models for the breakwaters, a model for the new-type horizontal-inclined-plate open breakwater is developed in this study. Based on the VOF method, a numerical model for interaction between the waves and the horizontal-inclined-plate breakwater is established. Studies of impacts of a new type of the horizontal-inclined-plate breakwater upon the wave transmission coefficients are carried out by numerical simulation. The main impacts such as the wave steepness H/L, relative plate spacing D/H, relative plate width B/L, relative freeboard d/H and inclined-plate angle on the wave dissipation effects of the breakwater have been considered in this paper. From the analysis results it is found that the above factors have great influences on the wave dissipation effects of the breakwater, and the results are as follows: ①the horizontal-inclined-plate permeable breakwater has a better wave-absorbing effect than the horizontal-plate permeable breakwater. Under the action of the inclined plate, the transmission coefficients increase with the increase in the angle of the inclined plate, but the increase magnitude gradually decreases; ②with the increase in wave steepness, the transmission coefficients decrease first and then increase; ③with the increase in horizontal-plate spacing, the transmission coefficients increase; ④with the increase in the relative plate width of the breakwater, the transmission coefficients decrease; ⑤with the increase in breakwater level, the transmission coefficients decrease first and then increase. The analysis results show that the new-type breakwater structure has remarkable effects on wave energy dissipation and has a good application prospect in ocean engineering.