Abstract: For investigation of the characteristics of easy-to-float yet hard-to-separate fine coal flotation process,quantitative evaluation is made of the flotation selectivity of the representative fine coking coal samples collected from Wuhai and Kailuan mining areas,through experimental study of kinetics,determination of distribution of oxygen-containing functional groups on sample surface using X-ray photoelectron spectroscopic and infrared spectroscopic methods,and by reference to Fuerstenua upgrading curve.As indicated by test result,for the Wuhai sample,in terms of selectivity,the medium size fractions are the poorest while the finer size fractions are much better; with respect to the Kailuan sample,the three size fractions—0.025~0.125 mm,0.125~0.074 mm and ＜ 0.074 mm—become sequentially smaller in selectivity; with the decrease of size,the different density fractions in the same size fraction become smaller in difference of hydrophilicity index,this constituting the root cause underlying the difficulty in flotation of easy-to-float hard-to-separate fine coal.