Abstract: In order to investigate the distribution of Pu and Am in settling particles from dispersed plutonium material in de-ionized water, settling particles from dispersed plutonium material were leached through shaking in de-ionized water, then the aqueous phase was classified by four methods. The contents of Pu and Am in the aqueous phase were determined using isotope-dilution analysis. The contents of Pu and Am in the aqueous phase rise quickly at the beginning of leaching, and then turn to be stable gradually. However, the rising rate of Pu content is faster than Am. The mass fraction of Pu and Am in the solution (including small colloid particles) are about 5×10^-9-1×10^-8 and 2×10^-13, respectively. Our results demonstrate that most of Pu is soluble state (including small colloid particles) in the aqueous phase, while most of Am is attached to the settling particles or contained in the settling particles.