<p>The 2-ethylhexyl phosphonic acid mono 2-ethylhexyl ester (HEHEHP) extractant exhibits a strong affinity for uranium (U(VI)) and thorium (Th(IV)), facilitating their extraction but complicating their stripping. After prolonged cycling, the HEHEHP organic phase accumulates significant amounts of U(VI) and Th(IV), which not only degrades the extractant’s recyclability but also poses radiological hazards to the working environment and personnel. This study systematically investigates the stripping process and mechanisms for removing U(VI) and Th(IV) from the HEHEHP organic phase using sodium carbonate (Na₂CO₃) as the stripping agent. Experimental results demonstrate that Na₂CO₃, owing to its high alkalinity and strong CO₃²⁻ dissociation, exhibits excellent U(VI) stripping efficiency. A novel approach combining "complete saponification with sodium hydroxide (NaOH) followed by low-concentration Na₂CO₃ stripping" was proposed, achieving efficient U(VI) stripping and separation. The optimal stripping conditions were determined as follows: a Na₂CO₃ concentration of 0.25&#xa0;mol/L, an organic-to-aqueous phase ratio of 1:2, and a temperature of 30&#xa0;°C. Under these conditions, a two-stage cross-flow stripping process achieved a U(VI) stripping efficiency of 99.35%, with a uranium product purity of 83.72%. By analyzing the ionic states of U(VI) and Th(IV) at varying pH levels, the migration and transformation behaviors of these elements in carbonate media were elucidated. At pH &gt; 10, Na₂CO₃ stripping primarily converts U(VI) into Na₄UO₂(CO₃)₃ while Th(IV) precipitates as Th(OH)₄, enabling effective separation of U(VI) and Th(IV). This research provides a theoretical foundation and a practical methodology for removing radioactive elements in rare earth separation processes while enabling the resource recovery of uranium and thorium.</p>