Abstract：Objective：To observe the effects of the modified Si breathing exercise based on the concept of "Zero- Time Exercise" on pulmonary function and dyspnea scores in patients with chronic obstructive pulmonary disease （COPD）. Methods： A total of 80 stable COPD patients admitted to The First Affiliated Hospital of Henan University of Chinese Medicine from December 2024 to June 2025 were selected and randomly divided into a trial group and a control group using the random number table method，with 40 cases in each group. During the study，three cases dropped out from the control group and two from the trial group，resulting in 37 cases in the control group and 38 cases in the trial group for final analysis. The control group received conventional treatment combined with traditional pursedlip abdominal breathing exercise，while the trial group received conventional treatment combined with the modified Si breathing exercise based on the Zero-Time Exercise concept. Pulmonary function indicators [forced expiratory volume in 1 second （FEV1），ratio of forced expiratory volume in 1 second to forced vital capacity （FEV1/FVC）]，dyspnea scores [modified Medical Research Council （mMRC） dyspnea scale]， 6-minute walking distance （6MWD）， and exercise adherence scores were compared before and after treatment. Results： Before treatment， there was no significant difference in pulmonary function indicators between the two groups （P＞0.05）. After treatment，FEV1 and FEV1/FVC levels were higher in the trial group than in the control group （P＜0.05）. Before treatment， there was no significant difference in mMRC scores between the two groups （P＞0.05）. After treatment，the mMRC score was lower in the trial group than in the control group （P＜0.05）. Before treatment，there was no significant difference in 6MWD between the two groups （P＞0.05）. After treatment，the 6MWD was greater in the trial group than in the control group （P＜0.05）. Before treatment，there was no significant difference in exercise adherence scores between the two groups （P＞0.05）. After treatment， the exercise adherence score was higher in the trial group than in the control group （P＜0.05）. Conclusion：The modified Si breathing exercise based on the concept of "Zero-Time Exercise" significantly improves pulmonary function，exercise tolerance，and dyspnea symptoms in patients with COPD，while also enhancing exercise adherence.