Abstract: Amidopodands, such as N, N, N′, N′-tetraoctyldiglycolamide(TODGA) have been evaluated as an efficient extractant for the separation of actinides(Ⅲ) and lanthanides(Ⅲ) from high level liquid waste(HLLW). Oxalic acid, which was treated as an aqueous complexing agent, was employed to prevent the extraction of some important fission products (e.g. Pd, Zr). However, the influences of H₂C₂O₄ on the TODGA-Ln(Ⅲ) extraction process remained unexplored. With TODGA or the mixture of TODGA and tributyl phosphate(TBP) as extractant, the extraction performance of Nd³⁺ was studied according to the varied amount of oxalic acid and nitric acid. The concentration of H₂C₂O₄ in organic phase was determined and the coordination of H₂C₂O₄ with Nd³⁺ in organic phase was studied using the method of UV-Vis absorption spectrum analysis. The results show that the distribution ratios of Nd³⁺ increase with the concentration of nitric acid at the range of 1.0-3.0 mol/L and increase with H₂C₂O₄ concentration at the range of 0.1-0.5 mol/L. The extracted oxalic acid in the organic phase decrease with the concentration of nitric acid at the range of 1.0-3.0 mol/L without coordination with Nd³⁺.