Abstract: In order to explore the coal slime water sedimentation effects obtained with the use of different agents, and the influence of slime water concentration on flotation process, sedimentation test is made with the slime water of the 10^# raw coal treated by Wuhushan Plant as the object and the use of sodium polyacrylate polyacrylamide copolymer as flocculant and diallydimethyl ammonium chloride as coagulant. Test result shows the use of compound agent can lead to significant improvement of clarity of circulating water, higher overall plant circulating water utilization efficiency, reduction of unit volume of make-up water to 0.085 m³/t and reduction of circulating water density to 0.5 g/L; and after reduction of density of circulation water, while maintaining the yield of clean coal, the ash of flotation concentrate is dropped from 13.21 % to 11.00% with a decrease by 2.21 percentage points.