Abstract: In order to achieve a better result in flotation of the coal slime which is liable to undergo degradation in water, analysis on size, density and lithology of the coal sample, and batch-flotation test are both made to explore the effect on slime flotation produced by different proportions of mudstone in dirts from mining seam's partings and different proportions of such dirts in coal attaining a higher yield of flotation concentrate product and recovery of collectors. As revealed by test result, the increase of proportion of mudstone in dirts can lead to decrease of yield of concentrate and recovery of combustible matter; the increase of content of dirts in coal slime can cause the rise of concentrate ash and drop of recovery of combustible matter; when the collectors KS712 and KS736 are respectively used at an equal dosage of 25 g/t, the yield and ash of the concentrate products are 51.38% and 56.15% in the former case, and 11.34% and 12.91% in the latter case, respectively; it can be seen that the collector KS712 is exceedingly good in selectivity and the collector KS736 exhibits an extremely high collecting capability; and with the use of both collectors for flotation of the fine coal which is susceptible to degradation in water, the flotation efficiency can get effectively improved.