Objective To clone the mature chain of hIL-22 and express the protein in E.coli efficiently.Methods The gene region of human IL-22 was cloned by RT-PCR and Nest PCR.After sequence identification,the hIL-22 gene encoding mature chain was inserted into expression plasmid PQE3.0 and transfected into E.coli M15.By the induction of Isoproplyl β-D-1-thiogalactopyranoside(IPTG),the recombinant hIL-22/His protein was effectively expressed in E.coli M15.The recombinant protein was purified by affinity chromatography.SDS-PAGE and Western blot were used to identified the recombinant hIL-22/His protein.Results The expression vector hIL-22/PQE3.0 was constructed successfully.The objective protein hIL-22 mature chain was expressed by bacterial cells as inclusion body.The molecular mass of the protein was confirmed by SDS-PAGE as an 18kD protein.Conclusion The pruified hIL-22/His recombinant protein can be used to make further study of cancer research.