The recombinant human interferon gamma for injection is prepared by lyophilization of Escherichia coli which efficiently expresses the human interferon gamma gene, after fermentation, isolation and high purification. It has strong immunoregulatory function, enhances antigen-presenting cell function, accelerates immune complex clearance and enhances phagocytosis of foreign bodies, has two-way regulation of lymphocytes, enhances antibody-dependent cytotoxicity, and enhances certain immune-active cells. HLA class II antigen expression.