The oxidation behavior of Ti40 alloy in 1000~1500℃ were researched. Analysis the organization and the elements change of the oxide surface and from surface to matrix with OM,XRD and EDS. The results shows that the oxide surface has the evaporation of the V₂O₅, grow up of the TiO₂, and due to the stress exceed the oxide film strength makes the oxide film cracking and spalling. When the oxide film spalled, The TiO₂ and Cr₂O₃ mix oxide layer become the new oxide layer, It with the enrichment layer of V, Cr elements have a good ability to resist the O element getting to the matrix.