The invention belongs to the technical field of spent fuel post-treatment, and discloses a process for purifying zirconium in a Purex flow plutonium purification cycle. 30% tri-butyl-phosphate (TBP)-kerosene is adopted as an extraction agent 2AX in a 2A extractor, so as to recover uranium and plutonium and purify fission fragments. The process comprises an extraction section and a washing section; and the concentration of a nitric acid in a 2AF feed liquid is 3.5-3.7mol/L, and 2AS is an HNO3 solution of which the concentration is 0.8-0.85mol/L. The process has the advantages that the plutonium yield is greater than 99.9%, and the purification coefficient of zirconium is greater than 100.