Objective:To set up an effective and simple purification method to obtain highly purified prokaryotic protein of PDCD5 and study its stability. Methods:Recombinant PDCD5 protein expressed in E. coli was accumulated as an inclusion body. After washing, the inclusion body was denatured, renatured, digested with thrombine and then purified by two steps of chromatography. The purity of the products was analyzed by capillary electrophoresis and the stability was identified by SDS-PAGE. Results:Capillary electrophoresis showed that the purity of protein was 100%, and molecular weight was 15 800 with pI 5.9. Further bioactivity assay indicated that the purified PDCD5 could enhance the apoptosis of HL 60 cells withdrawing cytokine, which was in a dose dependent manner. Stability analysis showed that the PDCD5 protein was sensitive to temperature and easy to degrade at 4 ℃ and 25 ℃. However, it was relatively stable at -20 ℃ or lyophilized. Conclusion:Highly purified and stable recombinant PDCD5 protein was obtained, which lays a foundation for the functional study and application investigation of PDCD5 .