The oxidation reactions of different tool materials under high temperature were derived from the theory of Gibbs free energy function, and the experimental study on the high temperature oxidation of tool materials was carried out. Cemented carbide (YG8), coated cemented carbide and ceramic tool materials were used in this study, and the oxidation products under high temperature were analyzed by SEM and XRD. The results showed that the WC and Co were oxidized into WO₃, Co₃O₄ respectively in the high temperature oxidation tests. With the increase of temperature, oxidation behavior is more severe. For the ceramic tool, onlyTiC is oxidized into TiO₂, which showed very good antioxidant properties. The order of oxidation resistance of the three kinds of tool materials is as follows: Ceramic Cutting Tools > Coated Cemented Carbide > YG8.