Abstract Objective MMP-9 has been shown to play an important role in the formation of COPD and emphysema. This study is aimed to investigate the role of Sirtuin1(Sirt1) in matrix metalloproteinases 9 (MMP-9) expression in alveolar macrophages(AMs). Methods The AMs were cultured with or without cigarette smoking extract (CSE) stimulation. Resveratrol and siRNA interference was employed to investigate the regulation of MMP-9 by Sirt1. Results MMP-9 expression was increased significantly due to 1% CSE stimulation. However, this effect can be antagonized by the Sirt1 agonist resveratrol in a concentration dependent manner. MMP-9 expression in AM cells was increased significantly after siRNA interference (P <0.05). Conclusion Sirt1 can inhibit the expression of MMP9 by AM, and it may play a protective role in COPD