Gradient Zr/ZrN/Zr layer was deposited as a diffusion barrier between the NiCrAlYSi The overlay coating and Ni-base superalloy DZ125 by arc ion plating(AIP). The microstructure and high-temperature oxidation behavior of the diffusion barrier were studied. The results show that the gradient diffusion barrier is homogeneous and compact, and has strong bond strength with the substrate. The diffusion barrier is composed of three layers, among which the inner and outer layers are rich in Zr, and the middle layer is rich in ZrN. The main phase structure of the diffusion barrier is ZrN(200). During high temperature oxidation at 1100°C, the Zr/ZrN/Zr/HY3 compound coating system presents excellent oxidation resistance.