Abstract: Raw coal removed reject by two-product or three-product heavy medium cyclone in Datong mining area,can used as high quality thermal coal product. Traditional views focus on the function of thickening suspension in second stage of three-product heavy medium cyclone,which is beneficial to remove reject as much as possible with less coal carried into it. The actual production shows that the two-product heavy medium cyclone has the same separation result as the three-product one under the condition of stable separation density,however,the two-product cyclone is preferred as a result of high separation accuracy,large capacity and low power consumption.