Abstract: In order to improve the separation effect of coarse coal slime in Taiyuan coal preparation plant,on the basis of analyzing the quality of coarse coal slime in ＜ 3 mm size range,Separation test performed on 7 different size fractions of coarse coal slime in the low limit of 0.5 mm and 0.25 mm.The test result shows that the size range of feeding is the critical factor which influences TBS separation effects,when the size of feeding is 1.5-2.5 mm and 3-0.5 mm,the separation result is best.Under appropriate up-flowing water velocity,fine products with ash content of 8.50%-8.70% can be obtained,and with yield exceeding 84.9%,combustible material recovery is above 91%.When the up-flowing water velocity is added,the yield of clean coal will continue to increase,but the clean product quality will be significantly decreased.