In this paper, the slime flotation of Dongpang, Xiqu and Guandi were studied by using new micro-emulsion and diesel oil as collector respectively, the results showed that micro-emulsion was a better collector on flotation effectiveness. Compared with diesel oil at the similar clean ash content, the clean coal yield of Dongpang, Xiqu and Guandi were improved by 14.21%, 3.90% and 5.54%, respectively, and the oil saving rate reached up 75%∼79%. It indicated that the micro-emulsion had a faster flotation rate than diesel oil in account for the better synergistic effect on 2-octanol resulted from the flotation rate tests. According to the results of Zeta potential, it proved that the absolute value of Zeta potential was decreased by micro-emulsion, and it was beneficial to slime flotation. It can be seen that, the micro-emulsion, with the characteristics of strong collecting property, good selectivity and high rate of flotation, was an energy-saving and environmental friendly reagent. [ABSTRACT FROM PUBLISHER]