The oxidation behavior of four Cr-based coatings with different Al content in 1200 °C steam environment has been studied. Due to the internal and external double-layer Al₂O₃ and intermediate Cr₂O₃ layer structure, Cr₇₀Al₃₀ coating shows better performance than other coatings. The Cr₈₅Al₁₅ coating owns partial protective properties, showing a continuous Cr₂O₃ layer and internal Al₂O₃ layer. Cr₅₀Al₅₀ coating and Cr coating presents obvious diffusion behavior with TZM substrate, which leads to the decrease of oxidation resistance of the coating. In this study, the effect of Al content on the oxidation behavior of the coating was discussed in detail.