Abstract: with an aim to determine the heavy medium cyclone's optimum separation parameters according to the requirements on structure of coal product, the following two models are developed based on results of test and analysis of the effect on separation density produced by various working parameters of the cyclone, and through regression analysis using the statistic of products and service solution(SPSS) software:the relational mode of actual separation density with various working parameters, and the relational model of separation density with product structure. As revealed by study results, the actual separation density of the first stage of the cyclone is positively correlated with the density of qualified medium and negatively correlated with the content of magnetics; the yield of clean coal is correlated positively with separation density and negatively with raw coal ash; and the ash of clean coal assumes a positive correlation with the separation density.