Objective To construct bioreactor with housefly to express human insulin.Methods Four recombinant expression plasmids were transferred respectively into the new fertillized eggs of housefly by electroporation.The first generation was screened with G418 after the founders were incubated to adults.Human insulin was detected by radioimmumoassay, Tricine-SDS-PAGE and Western-blot in samples of maggot of the second generation collected at the time of 96?hours.Results All four recombinant expression plasmids could express human insulin in housefly. Conclusion The housefly maggot has the ability of processing post-translation insulin genomic gene.So housefly can be used as bioreactor to produce human insulin.