Abstract: Hastelloy C-276 alloy is the preferred substrate material for preparing second generation of high temperature coated conductors by ion beam assisted deposition. As to Hastelloy C-276 alloy substrate, the Y₂O₃ amorphous film was prepared directly on the Hastelloy alloy surface via solution deposition planarization technology to meet the subsequent requirements. The effects of precursor stability, precursor concentration, heat treatment temperature and coating times on surface roughness were studied. Meanwhile, focused on the combination of high and low concentration, the coating efficiency was improved. Results show that the coating with a high concentration of 0.40 mol/L for 6 times, and then coating with a low concentration of 0.10 mol/L for 6 times, a high surface quality substrate with the surface average roughness R_a of 0.65 nm (5 μm×5 μm) is obtained, and the coating efficiency is improved by nearly 30% compared with the solution of a single solubility. When the concentration of precursor solution is high, the solution particle size is large, and the earlier coating effect is better. After that, the precursor solution with small particle size in low-concentration solution was used to modify the surface, which can greatly improve the coating efficiency.