Objective: To observe the clinical effects of bailing capsule on pulmonary function, airway inflammation and oxidative stress in patients with moderate to severe chronic obstructive pulmonary disease (COPD). Methods: Sixty patients with moderate to severe COPD were randomly divided into two groups: the control group and the treatment group. Every group contained 30 patients. The control group was treated with symbicort turbuhaler,and the treatment group was treated with symbicort turbuhaler plus bailing capsule. The pulmonary function and the inflammatory cells classification in induced sputum were measured before and after treatment (24 weeks). Serum superoxide dismutase(SOD), malondialdehyde (MDA) and total antioxidant capacity (TAOC) in serum were detected in the two groups. Results: Forced expiratory volume in 1 second (FEV1), FEV1% and FEV1/forced expiratory volume (FEV1/FVC%) were significantly improved after treatment in the control group and the treatment group compared to pretreatment (all P < 0.001), and all were better in the treatment group than that of the control group (all P< 0.05); The percentage of neutrophils was decreased and the percentage of macrophages was increased in induced sputum after treatment in both groups compared with pretreatment (all P < 0.001), and the changes are more significat in the treatment group compared to the control group (all P < 0.001); The levels of SOD and TAOC were enhanced, and level of MDA was reduced after treatment in the control group and treatment group compared to pretreatment (all P < 0.05), and the changes are more remarkable in. the treatment group compared to the control group (all P < 0.001). Conclusion:Bailing capsule could improve pulmonary function, reduce airway inflammation and inhibit oxidative stress in COPD patients.