Abstract: Objective:To explore the clinical characteristics of chronic obstructive pulmonary disease(COPD) with pulmonary interstial fibrosis(PIF).Methods:The data of clinical symptoms,radiographic features,high resolution computerized tomography(HRCT) of the chest,arterial blood gas analysis and lung function test of 20 cases with COPD and PIF were analyzed retrospectively,and compared with COPD patients.Results:Compared with COPD patients,the clinical features of the patients with COPD and PIF were lung Velcro rale,lung dispersion function decreased,chest X-ray showed diffuse pitting nodular shadows mainly for mesh shape honeycomb shadow(P0.01),and HRCT showed most frosted glass shape and mesh shape pitting shadow honeycomb lung(P0.01).Conclusions:The COPD and PIF damage the ventilation and diffusion function of pulmonary,which can lead to severe hypoxemia and affect prognosis.The HRCT of the chest can provide important evidence in clinical diagnosis.