Abstract: In order to rational use of the process performance evaluation index of dense medium separators for separating of coal,take the actual production data of three product dense medium cyclone in Shangshe coal preparation plant as research object,separately calculated and evaluated three indicators which affecting the process performance,and analyzed the influencing factors of each indicator and application conditions. The research results show that the ecart probable moyen have more objectivity and general comparison,the organic efficiency and total misplaced material is more pertinence,which has significant meaning for improving effect of dense medium separation of coal.