The recombinant pro-urokinase expressed in CHO cells was purified. The purification procedure was based on the following steps: micro-pore glass chromatography, CM-15HR chromatography, Sephacryl S-200 gel filtration. The yield was 46% and the purification factor was 700-fold. Small amounts of contaminating urokinase were removed by Benzamidine-Sepharose 6B affinity chromatography. Analysis by SDS-PAGE showed that the purity of pro-urokinase was 90% and the molecular weight was 52 ku.The specific activity of the purified pro-UK was 51 220 U/mg of protein. The characters of the recombinant pro-UK were consistent with that of the natural pro-UK.