Abstract: The extraction performance of La³⁺ and Ac³⁺ in hydrochloric acid medium was studied by using 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P₅₀₇) as extractant and sulfonated kerosene as diluent. The effects of acidity, saponification of extractant, La³⁺ concentration and concentration of salting-out agent on extraction were studied. When experimental conditions are as follows: the saponification degree of P₅₀₇ : 30%, the acidity of the feed solution: pH=2.45, the La³⁺ mass concentration: 32 g/L, and KNO₃ concentration of the salting-out agent: 3 mol/L, the extraction and separation properties of La³⁺ and Ac³⁺ are better. The separation factor (SF_La/Ac) between La³⁺and Ac³⁺ can reach 67.6. The results of a pilot experiment with the optimized experimental conditions show that the radioactivity in lanthanum oxide is effectively removed. The removal ratio of ²²⁷Ac in lanthanum oxide is approximately 89.97%, and the purified product of lanthanum oxide is obtained.