Objective To evaluate salmeterol/fluficasone combined with N-acetylcysteine in treatment of stable chronic obstructive pulmonary disease (COPD). Methods Sixty patients with stable COPD were randomized into treatment group(n = 30) and control group(n = 30). Patients in control group were given salmeterol/fluticasone twice per day ; while patients in treatment group in addition to salmeterol/ fluticasone, also took N-acetylcysteine 0.6 g three times per day. The course of treatment lasted for four weeks. Pulmonary function was measured in all patients; interleukin-8 (IL-8), tumor necrosis factor α (TNF-α), superoxide dismntase (SOD) and malondialdehyde (MDA) in blood serum and induced sputum were determined. The white cell count and classification in sputum smear was examined and the quality of life (QOL) of patients was evaluated. Results FEV1, FEV1 %, QOL evaluation, IL-8, TNF-α, white cell count and the percentage of neutrophil granulocytes in induced sputum after treatment were significantly improved compared with those before treatment in control group (P <0.05 or P <0.01). FEV1, FEV1%, QOL evaluation, SOD and MDA in blood serum, IL-8, TNF-α, SOD and MDA, total white cell count, the percentage of neutrophil granulocytes and macrophage in induced sputum after treatment were significantly improved in treatment group (P <0. 05 or P <0.01). The differences in SOD and MDA in blood serum and the percentage of neutrophil granulocytes in induced sputum smear between treatment group and control group were staffsticaUy significant (93 ± 8) × 10-6 U/L, (4. 0 ± 1.0) × 10-3 mmol/L and 0. 5 ± 0. 3 vs (85 ± 10) ×10-6U/L,(4.2±1.1) ×10-3mmol/Land0.6±0.2; allP<0.05. Conclusion Combination of salmeterol/fluticasone and N-acetylcysteine has better therapeutic results in treatment of airway inflammation of stable COPD.