Objective To explore the role of Sestrin2 in pulmonary alveolar type II epithelial cell injury induced by cigarette smoking and its mechanism of action. Methods The cell injury model was induced by cigarette smoke extract (CSE) in the human pulmonary alveolar type II epithelial A549 cells. The generation of ROS was detected by DCFDA fluorescence probe. The levels of inflammatory factors TNF-α and IL-8 were determined by ELISA, and the expression of Sestrin2 and the peroxiredoxin, Prx-SO_2/3 H, was detected by Western blot. In addition, all the events were also measured in the A549 cells which were transfected with Sestrin2 siRNA and treated with azithromycin. Results After the CSE treatment, the expression of Sestrin2 in the A549 cells was decreased, the expression of Prx-SO_2/3 H was increased, the ROS production, secretion of cytokines TNF-α and IL-8 were increased ( P < 0.05). These changes were partly reduced by azithromycin, indicating that azithromycin significantly relieved CSE-induced oxidative stress and inflammatory injury. Silencing of Sestrin2 in the A549 cells result ed in an increase of Prx-SO_2/3 H expression, ROS production and the secretion of the cytokines TNF-α and IL-8. However, oxidative stress and inflammatory injury were not alleviated with the addition of azithromycin in the Sestrin2 siRNA silencing A549 cells. Conclusions Sestrin2 plays an protective role in the pulmonary alveolar type II epithelial cell injury induced by cigarette smoking through negatively regulating the level of intracellular ROS via catalyzing the reduction of the hyperoxidized peroxiredoxin Prx-SO_2/3 H.