In order to further study the corrosion behavior of β-Nb second phase particles (SPPs) in zirconium alloys, a bulk 90Nb-10Zr alloy was prepared using vacuum non-consumable arc furnace based on the chemical composition and crystal structure of β-Nb SPPs. The 90Nb-10Zr alloy was corroded in 500 ℃ and 10.3 MPa super-heated steam in a static autoclave for 1 h and 7 h. X-ray diffraction, scanning electron microscopy and transmission electron microscopy were used to characterize the microstructure of the oxide film formed on the alloy. The results revealed that the monoclinic Nb2O5 was formed directly when 90Nb-10Zr alloy was corroded for 1 h, because the corrosion medium was directly contact with the outer surface of the alloy. When 90Nb-10Zr alloy was corroded for 7 h, the oxide film on the alloy was double-layer structure: the outer layer was monoclinic Nb2O5 and the inner layer was tetragonal NbO2 since the occurrence of further corrosion required the internal diffusion of the oxidizing substances in the corrosion medium. No single oxide of Zr was detected in this study. This oxidation process can reasonably explain the relationship between the Nb content and the corrosion behavior of Nb-containing zirconium alloy in super-heated steam.