Abstract: To solve the problem of difficult slurry settling in coal slurry treatment process,flocculation settling test was carried out to determine optimal reagent kinds and dosage according to properties of coal slurry,then industrial test is made on this basis. The results show that concentration of thickener overflow is up to 8. 50 g/L,particles existing in turbid liquid level is faster settling as well as supernatant turbidity is lower,and that the best settling effect of coal slurry is obtained when raw coal consumption is up to 20 g/t,46. 7 g/t using PAM-2010 flocculant,PAC coagulant respectively under test condition.