For the structures of permeable breakwater which are widely used in practical engineering,the relationship between the ratio of block diameter of core material to the equivalent width of dike D/Bswl and the dimensionless wave steepness H/(gT2) is analyzed through a series of sectional model tests.We propose improved empirical formulas of the transmission coefficient of permeable breakwater based on previous researches.The results and analysis show that the formula can be used to calculate the transmission coefficient of the permeable breakwater under regular waves ,and can be used for future reference in relevant engineering design.