Abstract: The cost of flotation production reagent is high for Nanliang coal mine of Shaanxi province, accounting for 84.5% of the plant cost. In addition, previous experiments indicated that the compound collectors such as GF and FO could improve the floatation efficiency, but the dosage of flotation reagents was high. In order to improve the flotation efficiency, decrease the dosage of regents, save costs and create more economic values, the effect of compound collectors on coal slime flotation was studied systematically in this work. By using sec-octanol as foaming agent, kerosene mixed with n-octylamine, n-decanoic acid, dodecane and methyl oleate respectively as collectors, the flotation experiments were conducted for the coal slime with particle size larger than 0.0385 mm. The flotation results showed that the compound collectors of methyl oleate and kerosene (mass ratio of 1∶6) exhibited the best flotation effect. The cleaned coal yield increased from 43.14% by kerosene to 61.70% by compound collectors, and the corresponding ash content changed from 9.50% to 9.61%. Meanwhile, the recovery rate of combustible substance increased from 42.98% to 61.48%. The excellent flotation effect of methyl oleate compound collectors was attributed to the higher wetting heat and adsorption energy between the oxyester group of methyl oleate and the oxygen-containing function groups of coal molecules, and the lower frontier orbital energy gap, which was helpful for the absorption on the coal surface and improvement of the hydrophobicity of coal. The results of X-ray diffraction, infrared spectrum and scanning electron microscopy showed that the ash content in the cleaned coal after flotation significantly decreased with only tiny fine mud particles attached on the surface of coal particles, indicating that the combination of methyl oleate and kerosene is an ideal compound collectors for slime flotation.