In this study，the transmission coefficient of a new type of pile-supported permeable breakwater is analyzed by a sectional method.The transmission coefficient of the whole breakwater can be expressed by multiplying the calculation results of the following three parts，including the upper retaining wall and the porous plates，the horizontal platform，and the piles.At the same time，this study establishes the wave numerical flume using the FLOW-3D software.The analytical results are compared with the numerical results，which have good agreement.In addition，this paper also carries out the expand analysis of the influence of the porosity and the length of the horizontal platform on the transmission coefficient by using the proposed calculation method.The results show that the transmission coefficient is apparently influenced by the increasing length of the horizontal platform，and the effect of porosity ε changes not obviously when ε＞20%.