Abstract: Elevated temperature oxidation behavior and mechanism of the Fe-12Cr-2.5W-0.4Ti-0.3Y2O3 Fe-based super alloy prepared by mechanical alloying were investigated by stastic oxidation test through XRD, SEM and EDS. The results show that oxidation degree of the alloy increased with the elevation of temperature, and with the extension of time the speed of mass gain decreased. And the curves of gained mass were liner to parabola. Furthermore, After oxidation for 80 h at 650 ℃ and 850 ℃, the oxide on surface was mainly Fe2O3. The oxide layers consisted of two layers, the outside layer was Fe2O3 and the inside layer near the matrix was mainly compound of Fe2O3 and Cr2O3. The oxide layer obtained at 650 ℃ was approximate 10 μm and compact with preferable oxidation resistance, while the layer obtained at 850 ℃ was more than 25 μm with phenomenon of desquamation and discontinuous of its inside layer near matrix which had lost its ability of protection.