Objective To explore the clinical effects of tiotropium in the treatment of patients with stable chronic obstructive pulmonary disease (COPD) and assess their lung function. Methods 142 patients with stable COPD in our hospital were selected.They were randomly divided into the control group and the observation group by random number table, 71 patients in each group.The control group used conventional treatment, and the observation group was simultaneously given tiotropium inhalation.The clinical efficacy and COPD symptom scores (CAT score) were observed, the pulmonary function was evaluated. Results The significant remission rate of the observation group was 88.73% (63/71), which was higher than 76.06% (54/71) of the control group, the difference was statistically significant (χ2=9.51, P 0.05). Conclusion Tiotropium bromide has better clinical effect for the patients with stable COPD.It can significantly improve symptoms and lung function, and it is safe. Key words: Pulmonary disease, chronic obstructive; Lung function; Tiotropium