The primers were synthesized according to the hlL-33 cDNA sequence in GeneBank.The hIL-33 was amplified by RT-PCR from humanfibroblastcell line(L929),the PCR product was inserted into pUC19 vector.The IL-33cDNA confirmed by sequencing was inserted into expressing vector PQE30 and expressed in E.coli M15 strain.IL-33protein expression was induced by IPTG and purified by Ni-NTA affinity chromatography.The recombinant IL-33 was identified by Immunoblot and its biological activity was analyzed.