Single crystal superalloys with a protective coating are widely used in the hot section of gas turbine. However, due to the differences in composition, microstructure and properties between the coating and the single crystal superalloy, various elements diffuse at the interface during service. These results thus reduce the long term microstructure stability and mechanical properties of the alloy. In this paper, two typical reactive elements doped coatings, NiAlHfZr and NiCrAlYSi, were deposited on a high Mo, low Re Ni₃Al-based single crystal superalloy (IC21) by multi-arc ion plating technology. The oxidation resistance performance, interdiffusion behaviour and microstructure evolution of the coating/alloy interface were investigated via isothermal oxidation at 1100°C. At the same time, thermodynamic calculations were carried out using Thermo-Calc software. Focusing on the effect of Al and Cr content on the stability of the interfacial microstructure, to guide the coating design of the IC21 alloy. The results showed that the interdiffusion zone (IDZ) and secondary reaction zone (SRZ) were formed at NiCrAlYSi/IC21 interface, α-Cr and the topologically Close-Packed Phases (TCP) were precipitated, respectively. TCP consists of Mo, Cr and Re elements. Meanwhile, no TCP phase was precipitated at the NiAlHfZr/IC21 interface. By calculating and discussing the precipitation driving force and thickness of the IDZ and SRZ zones. It was found that the diffusion of Al and Cr from coating into the alloy promoted the precipitation of Mo-rich phases. Therefore, for the IC21 alloy, a coating design with low Cr (18 wt.%) and moderate Al (8-10 wt.%) may be more suitable.