Abstract: In order to solve the shortage problem of coking coal in China and to expand the coking coal resources, taking the heavy medium prepared middlings (wi th a particle size of 50~ 0 mm and ash content of 36.63%) from Matou Coal Preparation Plant as the study object, the experiments on the crushing, high cone angle cyc lone separation and step by step releasing were conducted.The Leica DM4500P reflection microscope was applied to the micro component analysis on the middlings an d the different density products.The results showed that the fine particle middlings form Matou Coal Preparation Plant could be effectively separated with the high cone angle cyclone.With the step by step releasing experiment, the ash content would be 13.4% and the production rate of the cleaned coal would be 12.85%.