The first-principles based on the density functional theory was applied to calculate the structure parameters, bond units and electronic structure of the oxidation mechanism for the Pt-Zr solid solution under high oxygen atmosphere. The calculated conclusions show that the structure parameter of the Pt-Zr solid solution was changed by the oxidation reaction of Pt-Zr, so that the expansion along c axis is larger than the b and c axis in the Pt-Zr solid solution. As the oxidation of Zr is stronger than Pt, the electrons on the 4d orbit of Zr combine the electrons on the 2p orbit of O to bond and form the oxide of Zr, but Pt just acts as a bridge function during the wholly oxidize process. It is also found that our calculated results are in good agreement with the experimental phenomenon