Objective: To explore the effect of Sirt1 on the function of endothelial progenitor cells (EPCs) in rats with chronic obstructive pulmonary disease (COPD). Methods: A rat COPD model was established via smoking and endotoxin administration for three months. The peripheral circulating EPCs were isolated by gradient centrifugation, and their functions, cell cycle distribution, apoptosis, and Sirt1 expression were examined. The function changes of EPCs in the presence or absence of Sirt1 agonist and inhibitor were estimated; meanwhile, the expressions of Sirt1, FOXO3a, NF-κB, and p53 were also evaluated. Results: The proliferation, adhesion, and migration of EPCs decreased while the apoptosis rate was increased in the COPD rats. The expression of Sirt1 protein in EPCs of the COPD group was significantly lower than that in the control group (P<0.01). The overexpression of the Sirt1 gene using a gene transfection technique or Sirt1 agonists (SRT1720) improved the proliferation, migration, and adhesion, and decreased the apoptosis of EPC. However, Sirt1 inhibitor (EX527) decreased EPC functions in the COPD group. The effect of Sirt1 expression on EPC function may be related to reduction of FOXO3a and increase of NF-κB and p53 activity. Conclusions: Increased expression of Sirt1 can improve the proliferation and migration of EPCs and reduce their apoptosis in COPD rats. This change may be related to FOXO3a, NF-κB, and p53 signaling pathways.