Objective To observe the therapeutic effect of Huang Qi Glycoprotein (HQGP) on pulmonary fibrosis mice and discusse the mechanism of action.Methods:A total of 60 healthy ICR mice were randomly divided into the control group, the model group and the treatment group, with 20 mice in each group.The mouse pulmonary fibrosis model was established by intranasal instillation of bleomycin.From the next day, the treatment group was intraperitoneally injected with HQGP for 14 days.The model group and the control group were injected with equal volume of normal saline intraperitoneally; 7, 28 days after giving the drug, each group were sacrificed at 5 animal lung tissue.The effect of HQGP on the changes of the lung pathology, pulmonary index, the content of hydroxyproline (Hyp), superoxide dismutase (SOD), malondialdehyde (MDA) and transforming growth factor beta (TGF-β1) were observed.Results:Compared with the model group, the levels of pulmonary fibrosis in mice treated with HQGP were reduced in the 7th and 28th day.The levels of TGF-β1, Hyp, and MDA in lung tissue were significantly lower (P<0.05, P<0.01), and lung tissue SOD and pulmonary index increased significantly (P<0.05, P<0.01).Conclusion:HQGP may play an important role in the development of pulmonary fibrosis by reducing the synthesis of collagen and enhancing the antioxidant capacity of the body.