Abstract: The electronic structures of 2-mercaptobenzothiazole (MBT), 2-mercaptobenzothiazole (MBO) and 2-mercaptobenzothiazole (MBI) chelated collectors were analyzed by density functional theory. The effects of substituting N, O and S atoms on the properties of the collectors were systematically studied. The results show that MBO is composed of sulfur atoms near the Fermi level. S1 and S2 atoms are highly active and exhibit stronger electronic activity, indicating that MBO has stronger collection and selectivity than other two kinds of collectors. The interaction between MBO and minerals is the strongest through frontier orbit calculation, which can well explain the difference of the three chelating collectors. In the experiment, when three chelating collectors flotation chalcopyrite and pyrite, the recovery of chalcopyrite by MBO, MBT and MBI is 88%, 63% and 42% respectively, and the recovery of pyrite is less than 20%. The best flotation recovery reagent is MBO. Therefore, the collector MBO replacing O atom has the best selectivity for chalcopyrite, with stronger collecting ability and higher flotation recovery. The results provide theoretical guidance for further understanding the difference of flotation ability between chalcopyrite and pyrite and the development of new reagents.