Abstract: For accurately measurement of the decay data of ⁹¹Sr, the prerequisite was to obtain pure ⁹¹Sr specimens. Based on the analysis of parentdaughter relationships in the three relevant fission product decay chains, a two-step delayed chemical separation procedure for rapid isolation of ⁹¹Sr from neutron-irradiated ²³⁵U sample was developed. Two types of dicyclohexano 18-crown-6 extraction chromatographic resins were prepared with Kel-F powder and Amberlite XAD-7, respectively, as support. Sr can be rapidly and quantitatively absorbed on both resins and easily eluted from them with deionized water. A corresponding sub-rapid separation device was manufactured in which two delayed extraction chromatographic columns in series were incorporated. The usefulness of the procedure and device was verified by using real fission products solution obtained by dissolution of neutronirradiated ²³⁵U. The whole process is completed within 200 s. The ⁹¹Sr product is radioactively pure, with an overallrecovery better than 90%. The decontamination factor is greater than 10² for ⁹²Sr, and better than 10³ for other radionuclides. The quality of ⁹¹Sr specimens thus prepared can meet the requirements for its decay data measurements.