Objective To investigate the protective effects of Astragali on lung ischemia/reperfusion(I/R) injury in rabbits. Methods 24 rabbits were randomly divided into 2 groups-I/R group and intervention group. Rabbits were killed after the left lung was blocked for 2h and followed by 4h of ventilation. Astragali (2ml/kg) were fed before operation. Lung pathomorphologic and immunotype changes were observed and the percentage of damage alveoli was measure. Result In I/R group after reperfusion, the left lung became diffusely hemorrhagic and produced interstitial or alveolar edema. More serious mitochondria vacuolization and ridge dissolution were appeared in some alveolar epithelial cells. The right lung as control as normal. In intervention group, the left lung showed mild mitochondria vacuolization in a few alveolar epithelial cells .The percontage of elamage alveoli of in the left lung of the intervention group was significanthy lower than that of the I/R group (P＜005). The alveolar epithelial of the I/R group cell overexpressed Caspase-3(P＜001).Conclusion Astragali has a protective effect for the experimental rabbit lung ischemia reperfusion injury.