Abstract: Magnesite is an important magnesium-bearing mineral and is the main raw material for the production of magnesium.The adjustment of mineral surface wettability is a core issue in the flotation process, which is closely related to the surface properties of minerals.Therefore, an in-depth understanding of the surface properties of magnesite and dolomite is of great significance for their flotation separation.In this paper, the first-principles calculation method based on density functional theory(DFT) is used to study the properties of the cleavage planes of magnesite and dolomite, and its relationship with the floatability of two minerals.The results show that when the mineral crystals rupture, the surface structure of the two minerals shows obvious reconstruction.The relaxation of the dolomite surface atoms is more obvious than that of the magnesite.The surface free energy of the dolomite (101) surface is smaller than that of magnesite (101) surface.The orbital energy of the 3s orbital and 2p orbital electrons of the Mg atoms and the 3s orbital electrons of the Ca atom on the surface of the two minerals all span the Fermi level.The surface of the two minerals (101) shows a strong ionicity.