Abstract: In order to find effective sedimentation methods of difficult settling coal slurry in Housuo mine coal preparation plant,free settling test,settling test using coagulant and this test using coagulant ＆ flocculants are made on the basis of coal slurry properties. The result shows: the reason of difficult settling for coal slurry is caused by high content of clay mineral,water with small hardness and high concentration,strong electronegativity on the surface of particle; remarkable settling result of coal slurry can be improved by using coagulant ＆ flocculants,what ’s more,the best settling result is obtained at dosage of 200 mL coagulant and 9 mL flocculants,with supernatant liquor of 41. 90 NTU turbidity and initial settling velocity of 8. 13 cm/min.