In this paper, two sample groups, N5/(ZrB₂+ZrO₂)/NiCrAl and N5/ZrO₂/NiCrAl, were prepared on Ni-based single crystal alloy (Rene N5) substrate by electron beam physical vapor deposition (EB-PVD). Both sample groups were exposed to isothermal oxidation at 900 °C for 5 h and at 1000 °C, for 250 h, 300 h or 350 h. The microstructural evolution and deterioration failure behavior was investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results suggest that the introduction of ZrB₂ decelerates the interfacial reaction rate of the active diffusion barrier of Al₂O₃ but did not affect the final formation of the Al₂O₃ diffusion barrier with anti-diffusion properties. Moreover, the introduction of ZrB₂ prolongs the service life of active diffusion barrier structure and changes its failure mode.