Abstract: Objective To construct,express and purify the prokaryotic expression vector cystatin C(Cys-C). Methods The cDNA sequences of Cys-C gene in human embryonic kidney cell line HEK293 were detected from GeneBank by RT-PCR.The recombinant vector pET-30a(+)-CysC,identified by restriction enzyme restriction and sequencing,was transformed into E.coli.The Cys-C fusion protein was induced by IPTG and purified by Ni-chelating affinity chromatography. Results Sequence analysis showed 122 amino acids in peptide-encoded human Cys-C,which is consistent with the reported sequences in GeneBank(NM-000099.2).The expression of Cys-C gene was induced by IPTG.SDS-PAGE and ELISA showed that the expressed fusion protein accounted for 20% of the total bacterial protein.The molecular weight of recombinant protein was 20 000.The Ni²⁺-NTA agarose-purified SDSPAGE bind could specifically react with the commercially-available human Cys-C monoclonal antibody. Conclusion Cys-C can be expressed in E.coli and purified by Ni-chelating affinity chromatography.