Chinese hIFNcDNA deleted signal sequence was subcloned into downstream the P_RP_L promoter of the expression plasmid pBV220 by using of DNA recombinant technique.This recombinant plasmid can express hIFN-γ stably with high efficiency(up to 44.4% of the total bacterial soluble protein) in E. coli DH5α through thermal induction.The bioactivity assay showed that 0.45×10⁷～2.34×10⁷U rhIFN-γ were expressed in every liter of bacteria culture after preliminary purification and refolding procedures.