Abstract: ⁵⁵Fe in urea ¹⁴C capsule should be analyzed, so that the controllability and safety of pharmaceutical can be guaranteed. An analysis method of ⁵⁵Fe was established for the urea ¹⁴C capsule. The method is that the samples are first purified twice by AGMP-1 anion exchange resin, and then ⁵⁵Fe is determined by liquid scintillation counter (LSC) and the limit value of impurity radionuclide ⁵⁵Fe in urea ¹⁴C capsule is calculated, and the specificity, durability and detection limit of the method are verified. The results show that activity limit of the impurity radionuclide ⁵⁵Fe is less than or equal to 0.1% of the activity of ¹⁴C, the decontamination factor for ⁵⁵Fe with ¹⁴C is higher than 10⁵, the chemical recovery of Fe is 57%-67%, and the detection limit for 1 h is 0.4 Bq.