Abstract: The weathered shell leaching type rare earth ore is an important strategic resource in China. The rare earth leaching solution obtained by in situ leaching process has high content of Al³⁺ and is the main impurity ion. In order to separation rare earth ions from leaching solution by one-step way, the extraction behavior of a phosphate ester extractant, P0261 (2-ethylhexyl phosphate, 1 GA6FA 1 mixture of mono ester and diester), was investigated for rare earth ions La³⁺、Nd³⁺ in three simulated leaching solutions of NH₄Cl, (NH₄)₂SO₄ and NH₄NO₃, and the effect of impurity Al³⁺ on the extraction behavior of rare earth was also analyzed. The results show that the extractant P0261 has good extraction affinity towards rare earth ions La³⁺ and Nd³⁺ in the three kinds of ammonium salts solution. With the addition of Al³⁺, the extraction rate E of rare earth ions decreases with the increase of Al³⁺ concentration. E declines slowly when C(Al³⁺) at 0~300 mg·dm^-3, while the maximum reduction of E is 14.68%. By analyzed the load organic phase, Al³⁺ was easier to coordination bonds with P=O than RE³⁺, and the change of NH₄⁺ concentration has novel effect on the formation of P=O→RE coordination bonds, which was one of the reasons caused the change of rare earth extraction behavior. From experimental results, control the C(Al³⁺) below 300 mg·dm^-3 in in-situ leaching solution, the effect of impurity ion on selective extraction and separation rare earths by one-step way using extractant P0261 is accepted.