Abstract: In order to explore the flotation effect and interaction mechanism of methyl oleate on coal from Majialiang Mine, the coal slime flotation test, infrared spectrum, wetting heat measurement and quantum chemistry calculation methods were used to obtain the infrared spectrum, moistening heat, frontier orbital energy, adsorption energy and other parameters of methyl oleate, n-dodecane and coal sample before and after the interaction. The internal relationship and collection performance mechanism between parameters and methyl oleate, n-dodecane were studied. The results show the clean coal yield with methyl oleate is higher than that of n-dodecane at the same reagent dosage, and the reagent dosage is saved by more than 50%. The infrared spectrum of the interaction of methyl oleate with coal is weakened at —OH, and becomes stronger at —CH3, C—C and other hydrophobic groups, which not only covers the oxygen-containing functional groups on the coal surface, but also increases the hydrophobic groups on the coal surface after covering, so as to improve the hydrophobicity of the coal surface and the flotation effect. The wetting heat value of methyl oleate is much higher than that of n-dodecane, and the frontier orbital energy gaps of methyl oleate and n-dodecane are 8.45、4.82 eV, respectively by quantum chemistry calculation. The adsorption energy of methyl oleate is 193.50、199.24 kJ/mol on the surface of sulfur-containing and sulfur-free coal respectively, and the adsorption energy of n-dodecane is 102.49、114.82 kJ/mol on the surface of sulfur-containing and sulfur-free coal respectively. Therefore, methyl oleate has higher activity and is more likely to adsorb on the surface of coal. It is a high-efficiency collector for low rank coal slime flotation.