Abstract: To improve effects of slime flotation,the best flotation conditions of compound reagent which was the mixture of kerosene and aromatic AR reagent was investigated through orthogonal test. The flotation mechanism was introduced. The experimental results showed that,for compound reagent,when the flotation pulp concentration,dosage of collector and frother were 100 g / L,1000 g / t and 1000 g / t respectively,the clean coal yield,ash of clean coal,flotation perfect index could reach 59. 87%,12. 10% and 67. 51%. For traditional reagent,when the flotation pulp concentration,dosage of collector and frother were 60 g / L,1200 g / t,120 g / t,the clean coal yield,ash of clean coal,flotation perfect index could reach 57. 97%,11. 91%,65. 83%. Compound reagent was more superior to the traditional reagent in improving clean coal yield( 1. 90%) and flotation perfect index( 1. 68%). Through X ray diffraction analysis and infrared spectrum analysis,the separation effects of the compound reagent on quartz and coal particles was better than that of traditional reagent. The attachment of compound reagent on surface of coal particle changed its wettability and improved flotability. After flotation,the content of quartz,mica and kaolinite in clean coal decreased.