The present research investigates the effect of aluminum ions distribution on the removal of aluminum from rare earth solutions using saponified naphthenic acid. The effect of extraction type on the extraction rate of aluminum and rare earth was studied and the results indicated that aluminum influences the purity of rare earth seriously. For the removal of aluminum, the distribution fractions of aluminum ions and hydroxyl polymeric aluminum ions at different pH value at 0.15 mol/L initial aluminum concentration were calculated by MATLAB software. The plot of distribution fraction of aluminum ions and hydroxyl polymeric aluminum ions with pH value are obtained. Based on these, the effect of pH value and saponification value on the extraction of aluminum and rare earth were studied. The results show that the extraction rate of aluminum was highest at pH value 3.0 at initial aluminum concentration 0.15 mol/L in the absence of emulsification. This is consistent with the distribution of aluminum ions and hydroxyl polymeric aluminum ions. For the solutions containing low aluminum concentration, it is easy to separate aluminum from rare earth at 0.3-0.5 saponification value at pH value 3. (C) 2017 Elsevier B.V. All rights reserved.