Abstract: The crystal anisotropy of molybdenite makes its "surface" and "edge" have very different properties, which further affects the flotation behavior of molybdenite. Through density functional theory, the reasons for the differences in the properties of molybdenite "surface" and "edge" are demonstrated from the atomic level, and the effects of water, kerosene, and xanthate on the surface of molybdenite are discussed. The results show that the "surface" of the molybdenite is strongly hydrophobic and the "edge" is strongly hydrophilic. In addition, kerosene is mainly adsorbed on the S-containing atomic face of molybdenite by electrostatic interactions, whereas xanthate is adsorbed on molybdenum "edge" by the bonding interaction of the S atom in its C-S single bond with Mo atom at the molybdenite "edge".