Abstract: In this work, the process operation conditions of metal materials used in the evaporation and concentration process of the mother liquor after plutonium oxalate precipitation was simulated, and the corrosion behavior of zirconium alloy plate and its welded samples in the mixed oxalic-nitric acid was studied according to the requirements of GB/T 4334.3-2000. The corrosion rates were obtained by weighing method, the corrosion morphology of metal surface was observed by scanning electron microscope, and the concentrations of metal ions in the corrosion solutions were determined. The results show that the corrosion rates acquired by simulating corrosion tests are relatively low. The maximum corrosion rates of zirconium alloy are 0.001 0 g/(m²·h) for plate and 0.000 7 g/(m²·h) for weld, which are independent on the temperature and nitric acid concentration, and less than the values for stainless steel. Based on these results, we can understand why Zr-702 was selected as the material of evaporation and concentration equipment for the mother liquor of plutonium oxalate precipitation in the French reprocessing plant.