Abstract: The density functional theory(DFT) was applied to investigate the geometric and electronic structures of a series of xanthogen formates. According to the Klopman's generalized perturbation theory,the relationship between the flotation performance of collectors and quantum chemical parameters was analyzed by using the energy and shape of frontier orbitals,natural bond orbital charge,electronegativity,and hardness index. The results show that the bonding atom of xanthogen formates is the S atom in the C=S bond. These parameters such as the energy of the highest occupied molecular orbital(EHOMO),natural bond orbital charge and electronegativity can only infer the flotation activity of collectors. The selectivity of xanthogen formates is mainly related to that copper atoms on the chalcopyritesurface donate d-orbital electrons to the lowest unoccupied molecular orbital(LUMO) and second lowest unoccupied molecular orbital(LUMO + 1) of collectors and then resultin the formation of a back donation covalent π-bond,thus improving the flotation power for chalcopyrite and the selectivity against pyrite. The energies of LUMO and LUMO + 1 can be used to interpret the selectivity of xanthogen formates.