Abstract: The nanostructured CoNiCrAlY powder was prepared using the technology of planet mechanical milling. The oxidation behavior of conventional and nanostructured powder at 1 000 ℃ was investigated by the measures of X-ray diffraction and scanning electron microscope. The results show that the technique of planet mechanical milling could be used to prepare nanostructured powder and the average grain size of CoNiCrAlY powder is 11.2 nm after milled for 30 h. The anti-oxidation capability of CoNiCrAlY nanostructured powder is well improved. During the static oxidation of constant temperature at 1 000 ℃ for 100 h, the nanostuructured powder forms only a single α Al₂O₃ scale, while the conventional powder forms mixed oxide scale composed of α Al₂O₃ scale, mixed oxide and a small amount of θ Al₂O₃.