Abstract: High ash fine coal slime in western Guizhou was taken as study object in this paper. Size analysis, small float-sink test and flotation reagent system exploration were operated subsequently. Results show that, in this coal preparation plant, fine coal slime with size range lower than 0.045mm accounts for 43.30%, with ash content up to 47.97%, along with washability curves based on small float-sink test (ash curves is very steep), a conclusion can be obtained that this coal slime belongs to high ash-difficult to flotation-fine coal slime. Different collectors (diesel oil and n-dodecane), foaming agent (terpenic oil, DL-2-Octanol and MIBC) were compared as well. Results show when slurry concentration is 110g/L, collector chosen n-dodecane with concentration of 270g/t, foaming agent chosen MIBC with concentration of 6g/t, yield of flotation clean coal is 38.91%, with ash content of 11.14%, while that of tailing coal is 45.53%.