To observe curative effect of Yifei Capsule in stable phase of COPD and the impact on the expression of SIRT1 protein in the peripheral blood. Methods:A total of 70 patients in our hospital were randomly divided into control group (n=35)and observation group (n=35). Routine COPD treatment was given to the control group, and Yifei Capsule was given to the observation group aside from the conventional treatment. The treatment lasts for three months, and after the treatment term, pulmonary function changes, changes in quality of life and change of SIRT1 protein during the follow-up period were recorded. Results:1) After treatment, lung function and quality of life of both groups have improved significantly (P<0.05).This is more obvious in the observation group.(P<0.05); 2) After treatment, both groups showed an increase of peripheral blood mononuclear cells of SIRT1 protein(P<0.05),and this is more significant in the observation group(P<0.05). Conclusion:Yifei Capsule can slow down the progression of COPD, which may be associated with the increase in regulation of SIRT1 protein in the peripheral blood.