To mitigate the impact of interdiffusion reactions between the silicide slurry and the Ta12W alloy substrate during the vacuum sintering process on the oxidation resistance of the silicide coating, this study employed a micro arc oxidation pretreatment process to construct a Ta2O5 ceramic layer on the surface of the Ta12W alloy. Subsequently, a slurry spraying-vacuum sintering method was utilized to prepare a Si-Cr-Ti-Zr coating on the pretreated substrate. Comparative studies were conducted on the microstructural and phase compositions of the as-prepared coatings with and without the micro arc oxidation ceramic layer, as well as their isothermal oxidation resistance at 1600 ℃. The results indicated that the Ta2O5 oxide layer prepared at 400 V was more continuous and had smaller pores compared to that prepared at 350 V. After micro arc oxidation, the Si-Cr-Ti-Zr coating on the Ta12W surface consisted of an upper layer dominated by Ti5Si3, Ta5Si3 and ZrSi, a middle layer dominated by TaSi2, and a coating/substrate interfacial reaction layer dominated by Ta5Si3. The Si-Cr-Ti-Zr coatings with and without the Ta2O5 ceramic layer did not fail after isothermal oxidation at 1600 ℃ for 5 h, but the addition of the Ta2O5 oxide ceramic layer could delay the high-temperature oxidation rate of the coating.