The adsorption of phosphate ions and oleate ions onto CO₃^2- defects on dolomite (104) surface was studied by using density functional theory (DFT) calculation. The results showed that the CO₃^2- defects that were generated due to dolomite dissolution led to the enhancement of the activity of metal atoms on the surface, which was beneficial to the interaction between anions and mineral surface. The adsorption energies of H₂PO₄^- onto calcium atoms on the ideal dolomite surface and the defective dolomite surface were calculated to be -183.30 kJ/mol and -561.24 kJ/mol, respectively. Based on the calculation of density of states, it was found that after adsorption of H₂PO₄^- onto the calcium atoms on the surface of defective dolomite, the adjacent magnesium atoms still had strong activity, and the adsorption energies of oleate ions onto the magnesium atoms on the surfaces of the ideal dolomite and defective dolomite were -52.29 kJ/mol and -489.43 kJ/mol, respectively. Phosphoric acid ions and oleic acid ions were adsorbed together on the surface of dolomite, resulting in the floating of dolomite.