Abstract: Objective:To investigate the effects of erdosteine on the airway inflammatory reaction in mild and moderate chronic obstructive pulmonary disease(COPD) patients during the stable phase.Methods:Seventy-two mild and moderate COPD patients during the stable phase were randomly divided into the observation group and control group(36 cases each group).Two groups were treated with salbutamol aerosol combined with theophylline according to the COPD guideline,the observation group were additionally treated with 300 mg of erdosteine twice a day,and two groups were treated for 6 months.The clinical symptoms,pulmonary ventilation function,number of acute exacerbation,dyspnea questionnaire score,serum C reactive protein level,and sputum interleukin-8,tumor necrosis factor-α and myeloper-oxidase levels between two groups were analyzed and compared after 3 and 6 months of treatment.Results:The differences of the dyspnea questionnaire score,pulmonary ventilation function and serum C reactive protein level between two groups were not statistically significant after 3 and 6 months of treatment(P>0.05).After 6 months of treatment,the phlegm disappearance rate in observation group increased,the number of acute exacerbation in observation group was less than that in control group(P<0.05),and the levels of sputum interleukin-8 and tumor necrosis factor-α in observation group were significantly lower than those in control group(P<0.01).Conclusions:The erdosteine is an effective phlegm dissolving agent,which can inhibit the airway inflammation reaction,and is safe and effective in mild and moderate COPD patients during the stable phase.