Objective: To investigate the role of apoptosis in ventilator induced lunginury (VILI). in the role of ventilator-associated lung injury mechanisms; Methods: 50 healthy male Wistar rats were randomly divided for the control group (without mechanical ventilation after intubation) and mechanical ventilation group (after intubation mechanical ventilation: tidal volume 20ml/kg, frequency of 50 times / min, respiratory absorption ratio of 1:3, FiO2 21%, ventilation Time: 5h), observed before and after experimental changes in arterial partial pressure of oxygen; used Annexin-V/PI detected by double staining in lung tissue and alveolar lavage fluid cell apoptosis; get rats in each group, said the left whole lung wet weight, placed in oven within 80 ℃ said after 24h dry roasted dry weight, and calculate the lung tissue wet / dry weight (W / D) ratio; Preparation of lung tissue biopsies pathological examination; Results: The two groups of rats were no significant differences in arterial partial pressure of oxygen (p "0.05), mechanical ventilation and alveolar lavage fluid in lung tissue significantly increased apoptosis (p <0.01), mechanical ventilation in lung tissue wet / dry weight (W / D) ratio were significantly higher (p <0.01) , mechanical ventilation can be seen in lung tissue biopsy lung tissue edema; Conclusion: Mechanical ventilation can cause lung injury, lung cell apoptosis may, in its genesis and development play an important role.