Objective To investigate whether long term bronchodilator tiotropium has an acute bronchodilator effect on COPD patients. Methods 46 patients with stable COPD were enrolled in the study.Lung function test was performed before and at 10 min, 20 min, 1 h after inhaling tiotropium. FEV1 , FVC,FEV1/FVC, PEF25% -75% were measured by ambulatory spirometer. The patients were followed up after 1 month.Results The mean FEV1 was ( 1. 110 ±0. 34) L before inhaling tiotropiumand ( 1. 172 ±0. 359) L, ( 1. 221 ±0. 391) L, ( 1. 225 ±0. 392) L at 10 min,20 min, 1 h after inhaling tiotropium, respectively. FEV1 at 1 h after inhaling tiotropiumsignificantly increased compared with that before inhaling tiotropium. FVC also increased and reached highest at 1 h after inhaling tiotropium. PEF25%-75% at 1 h after inhaling tiotropium increased, but there was no significance difference compared with that before inhaling tiotropium. Mean FEV1 was 1. 287 Lafter 1 month, with significant difference compared with baseline. Conclusion Tiotropium can release the symptoms and improve compliance of COPD patients for its acute bronchodilator effect on COPD patients.