This paper introduces a new type of breakwater,i.e.semi-permeable caisson breakwater.By the hydraulic model test conducted in a glass wave tank,we measure the wave characteristic parameters in front of and at the back of the semi-permeable caisson breakwater at various wave heights and periods of the wave action.The objective of this project is to investigate the reflectivity of semi-permeable caisson breakwater under different wave conditions,and analyze the relationship between the period of the wave and wave steepness.Furthermore, we probe into the wave dissipation principle and performance of the breakwater.According to the test results,we select the the best combination of permeable rate and slope gradient,which provide a new way of thinking for the conceptual design and planning of wave protection and wave dissipation in the open port.