Abstract: In order to solve the problem of the slime water system in Wanglou coal preparation plant,the particle size composition analysis and the flotation test were done no the coal slime of the plant.The test result shows high content of the high ash fine particle slime in coal slime should affect flotation effect,under the condition of same flotation system.flotation column has obvious advantages in reducing ash content and improving the yield of clean coal.Economic forecasts show that the gross profit can increased by 50 million Yuan per year after transformation of flotation system,the economic benefit of project is extremely considerable.