The first-principle method based on the pseudopotential plane-wave is adopted to analyze O2 adsorption on the LaMnO3 (001) surface. The calculated results indicate that, LaMnO3 presents half-metal properties by calculating the band structure and density of states (DOS). In the MnO6 octahedron, the O-Mn-O bond is mainly covalent, on the contrast, O-La-O bond is mainly ionic. Molecular oxygen can adsorb on the LaMnO3 (001), M2 may be the most favourable adsorption mode. The adsorption mode leads to the formation of .The valence of Mn in the adsorption sites after adsorption of M1 and M2 is Mn3+0.25, Mn3+0.31, respectively. M2 may be the most adsorption mode that can make Pd 0 to shift Pd2+ more quickly in the process of direct synthesis of diphenyl carbonate (DPC) using the catalyst -Pd supported on the LaMnO3.