Abstract: Objective:To determine the expression of VEGF in pulmonary fibrosis patients and mice model,and its effect on disease.Methods:The expression levels of VEGF and α-SMA in lung tissue of pulmonary fibrosis patients and normal lung tissue were detected using immunohistochemical staining,and the correlation of positive expression of VEGF with severity of pulmonary fibrosis was analyzed.The mice model with pulmonary fibrosis was established using bleomycin injecting trachea of mice for 21 d,and the expression levels of VEGF and α-SMA in lung tissue of mice were detected using immunohistochemical staining.After treatment with VEGF164 antibody,the pathological damage and collagen expression in lung tissue of pulmonary fibrosis mice induced by bleomycin were analyzed using H&E and Masson staining,the lung tissue was evaluated using Ashcroft score,the mRNA levels of α-SMA and fibronectin in lung tissue were measured by Real-time PCR,and the changes of hydroxyproline content in lung tissue was detected using kit.Results:The positive expression of VEGF in lung tissue of patients with pulmonary fibrosis and bleomycin-induced mice were identified,and the expression of α-SMA was correlative with VEGF positive rate.After VEGF164 antibody blocking the expression of VEGF in lung tissue,the pathological damage and collagen expression in lung tissue of pulmonary fibrosis significantly alleviated and decreased,the mRNA levels of α-SMA and fibronectin decreased,and the changes of hydroxyproline content decreased.Conclusions:The expression of VEGF in patients with pulmonary fibrosis and bleomycin-induced pulmonary fibrosis mice are positive,and blocking the VEGF expression can relieve the PF induced by BLM.