Abstract: The accelerative effects of mixed organic acids of malonic and other organic ligand acids on mass transfer of U(Ⅵ) in ion exchange are studied by elution development. It is found that the migration rate of the elution peak of U(Ⅵ) increases and the delay-time decreases as the ratio of hydrocarboxylic and malonic acid increases , especially, for the mixed acid of citric and malonic acid, but little effect is observed on those two parameters for the mixed acids of dicarboxylic acids. Some exploratory explanations are given to the conclusions.Futhermore, the asymmetry of the elution chromatogram is explained from the point of view of the diffusion mechanisms of reversible ion exchange process.