The oxidation behavior of the Fe-9.96Ni-10.7Cr-6.49Al-0.25Zr-3.49Mo- 0.005B (wt%) (FBB8) alloy at 800 ℃ and 900 ℃ was investigated and the microstructural evolution of the oxide layer and substrate was also analyzed. The mechanisms by which zirconium doping influences the oxidation behavior of FBB8 are investigated, and a dynamic segregation mechanism is utilized to explain the differing effects of Zr at 800 ℃ and 900 ℃. At 800 ℃, the slow diffusion of Zr results in an oxide layer predominantly composed of alumina, during which Zr inhibits the diffusion of cations. In contrast, at 900 ℃, a composite oxide structure is formed, with zirconium dioxide embedded within Al2O3, leading to accelerated oxidation of the alloy. The NiAl phase acted as an aluminum reservoir during oxidation at 900 ℃. However, due to its small area-to-volume ratio, Al could not diffuse to the oxide scale/alloy surface, leading to internal oxidation in the alloy. This research provides a foundation for understanding the reactive element effect and offers data support for the development of Zr-containing alloys.