Abstract: The corrosion test of 1Cr18Ni9Ti stainless steel sheets was carried out in nitric-hydrofluoric acid of different concentrations, and then mechanical property test and microstructure observation were performed to explore the influence of various factors of acid pickling on the corrosion of ultra-thin-walled stainless steel sheets. The results show that acid pickling brings the most serious corrosion to sensitized stainless steel sheets. When the concentration of nitric acid in the etching agent is less than 20%, the higher the concentration of hydrofluoric acid, the higher the corrosion rate of stainless steel sheets is. When the concentration of nitric acid is higher than 30%, the mechanical properties decrease with the increase of hydrofluoric acid concentration, but the corrosion rate does not change significantly. Higher concentration of nitric acid and lower concentration of hydrofluoric acid should be used as the etching agent for ultra-thin-walled 1Cr18Ni9Ti stainless steel sheets.