High-temperature oxidation behavior of Ti-22Al-26Nb alloy was studied by thermogravimetry at 800 and 900℃. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) were employed to characterize the phase composition and morphology of oxide films. Results show that the oxidation of the alloy was parabolic at the transient stage, while it was approximately linear from 20 h to the end of the oxidation. Oxides mainly composed of TiO2, AlNbO4 and Nb2TiO7, and the oxide scale was stratified, which became more obvious with oxidation temperature increasing.