Abstract: The high temperature endurance test of G115 steel was carried out under different stresses at 625—700 ℃ to study its high temperature endurance performance, and the 1×10⁵ h long-term endurance strength of the steel was extrapolated by the Larson-Miller(LM) parameter method. The oxidation test of G115 steel was carried out at 650 ℃/27 MPa steam parameter for 2 000 h, and the surface and cross-section morphology, phase composition and microarea composition of the oxide film were studied and compared with those of T92 steel. The results show that under the action of reinforcement of copper-rich phase, the long-term endurance strength of G115 steel at 650 ℃ was 82 MPa, which was significantly higher than 53 MPa of T92 steel. The steam oxidation resistance of G115 steel was better than that of T92 steel, and the thickness of oxide film on the surface of G115 steel was about 102 μm, which was smaller than about 110 μm of T92 steel. The oxide film structure of the two was similar. The outer oxide layer consisted of coarse columnar Fe₃O₄, and the inner oxide layer consisted of fine Fe-Cr spinel and a small amount of Fe₃O₄; the outer oxide layer had many holes, and the tendency of spalling was relatively large.