Abstract: For tackling the problems encountered in the operation of the plant’s coal slurry water treatment system,work is made on improvement of the system following an analysis of the existing operating conditions.The work made includes optimization of the system,scientific determination of process norms and intensification of process management by taking effective measures.Practice shows that after optimization of the treating system,the concentration of washwater is reduced from 120 g/L to 80 g/L and that of circulating water is lowered from over 20 g/L to less than 300 mg/L,making it possible for the plant to see a noticeable increase of coal slime separation efficiency and clean coal yield,and realize coal washing with closed washwater circuit.