Abstract: To solve the problem of high content of coarse coal slime,low separation accuracy and big medium consumption of heavy medium cyclones,three taper angles hydrocyclone is used to separate coarse coal slime instead of FJ710 × 3 hydraulic classification cyclones; Moreover,structure,working principle,technical characteristic and parameters,application of the hydrocyclone are introduced and analyzed. The application shows that coarse coal slime is separated effectively and medium consumption is reduced obviously,and that capacity of washing raw coal is increased as well as quality of clean coal is improved better.