Abstract: In order to solve the problem of unreasonable design of coal slurry treating system in Chengzhuang colliery coal preparation plant,combined and thickened the slurry from lump coal and small coal separation systems,meanwhile,the coarse slime recovery system of the two systems above operated separately,and replaced the dewatering equipment. After the technology renovation and replacing pressure filtration equipment of the coal slurry treating system,the stability of the system improved and realized the wash water closed cycle in total plant,which obtained significant benefit.