254SMO is a typical austenitic stainless steel with 6% molybdenum which gives possible poor oxidation resistance property at high temperature.It may affect the hot working of 254SMO.The high temperature oxidation behavior of super-austenitic stainless steel 254SMO was investigated at 900 ~ 1 200℃,which is the temperature range of its hot working,in air by means of the method of mass gain,SEM/EDS and XRD.The results show that oxidation kinetics basically obeys parabolic law well.Oxidation mass gain is considered of different pattern at disparate scale of temperature with time.At the test temperatures,the oxidation layer is mainly composed of two different classes.One class is Fe2O3,and the other is Fe3O4,a variety elements involved in the formation of oxides.The former type is decreased as the temperature grows,and the latter class will be gradually disappeared at temperature above 1 050℃,and the worse oxidation resistance property is appeared at 1 050℃ and 1 100℃.As a result,the sensitivity to aging temperature of 254SMO is found.The oxide of Mo to volatilize,which is the main factor,causes the break of the continuity of oxides layer and increases the oxidation rate.