Objective: To explore the effect of smoking cessation intervention based on the timing theory on patients with chronic obstructive pulmonary disease (COPD). Methods: A total of 108 COPD patients admitted from January to December 2020 were selected and randomly divided into an observation group and a control group, 54 cases in each group. The control group was given routine intervention, and the observation group was given a smoking cessation intervention based on the timing theory, and the nicotine dependence, lung function, negative emotion and quality of life were compared between the two groups. Results: After the intervention, the smoking cessation rates in the observation group were lower than that in the control group in the discharge preparation period, adjustment period and adaptation period (P<0.05); After the intervention, the degree of nicotine dependence in the observation group was lighter than that in the control group (P<0.05); the lung function of the observation group was higher than that in the control group (P<0.05); the negative emotion of the observation group was lighter than the control group (P<0.05); the quality of life of the observation group was better than that of the control group (P<0.05). Conclusion: Smoking cessation intervention based on the timing theory applied to COPD patients can effectively reduce their nicotine dependence, enhance their lung function, promote the relief of negative emotions, and significantly improve the quality of life of patients.