Isothermal oxidation kinetics and oxidation mechanism of GH3535 superalloy was studied at 700 °C for 700 h. The morphology and component of the high-temperature oxide scale for GH3535 alloy was analyzed by SEM, XRD, EPMA and SRXRF techniques. The results show that the oxidation kinetics curve of GH3535 alloy follows the cubic law at 700 °C. Thickness of the oxidation film is about 5 μm and internal oxidation does not occur. The oxidation film has no obvious spallation and it is composed of NiO, Cr2O3, NiCr2O4 and NiMn2O4