Abstract: A systematic study on O₂ adsorption on CeO₂ (111) surface is carried out by use of the first principles calculations and density functional method. The formation of different reactive O₂ species near the different oxygen vacancies on CeO₂ (111) surface is investigated. And then on this basis, due to relatively strong interaction between peroxide O₂^2- and Au atom, Au can be adsorbed strongly on the CeO₂ (111) surface, and the adsorption energy is 1.8 eV. However, the Au atom can be weakly adsorbed nearby the superoxide O₂^- on the CeO₂(111) surface, and the adsorption energy is only 0.4 eV. The results provide an important theoretical support for CO oxidation on Au/CeO₂.