Abstract: In order to research the proportion of gangue and coal washed on the settlement of slime water in Zhanger coal preparation plant,in this article,the size composition of ﹤0.045 mm size fraction fine slime studied by laser particle size analyzer and main component of coal and gangue studied with the XRD.Take different proportion of the coal and gangue to carry out arqillation test,and analyzed quality of the clear liquid of slime water.The results show that,at the mass proportion of coal and gangue is 3∶1,the hardness reached to maximum value,that more facilitate the settlement of slime water in Zhanger coal preparation plant.From the aspect of increasing flotation efficiency and energy-saving and emission reduction,the proportion of gangue washed should reduced to speed the settlement of slime water in Zhanger coal preparation plant.