Abstract: The troubles with the coal preparation plant are escape of water from coarse coal slime sieve bend and poor performance of spiral separator.Based on result of analysis of existing operating conditions,work is made on optimization of coal washing system,so as to enable the sieve bend and spiral separator to work with a highest performance.Practice shows that through optimization,both equipment performance and product quality have been greatly improved in addition to respective reduction of moisture and ash of coarse slime by 1 and 0.50 percentage point,and according increase of its calorific value by around 0.38 MJ/kg,bringing about for the washery a significant economic benefit.