Abstract: This paper introduces the introduction and development process of hydraulic grade cyclone in China, and expounds its function in the recovery process of coarse clean coal slime. Through the analysis of the product specifications of the hydrocyclone, that due to the particles sink ratio exists, will inevitably lead to the same particle materials of light and heavy products mismatch, commonly known as the "anti separation effect, resulting in coarse coal slime ash super easy products. The fine seam pneumatic impact sieve instead of the hydrocyclone, which can resolve the coarse coal in the process, the problem of high marl.