AIM: To study the protective effect of Astragalus membranaceus on intestinal mucosa reperfusion injury and its mechanism after hemorrhagic shock in rats.METHODS: A total of 32 SD rats were randomly divided into four groups (n = 8, each group): normal group,model group, low dosage group (treated with 10 g/kg Astragalus membranaceus) and high dosage group (treated with 20 g/kg Astragalus membranaceus). The model of hemorrhagic shock for 60 min and reperfusion for 90 min was established. Therapeutic solution (3 mL)was administrated before reperfusion. At the end of the study, the observed intestinal pathology was analyzed. The blood concentrations of lactic acid (LD), nitric oxide (NO),endothelin-1 (ET-1), malondialdehyde (MDA) and the activity of superoxide dismutase (SOD), glutathione peroxidase (GSH-PX) in intestinal mucosa were determined.RESULTS: The intestinal mucosa pathology showed severe damage in model group and low dosage group,slight damage in high dosage group and no obvious damage in normal group. The Chius score in low dose group and high dose group was significantly lower than that in model group. The content of MDA in model group was higher than that in low and high dose groups, while that in high dose group was almost the same as in normal group. The activity of SOD and GSH-PX was the lowest in model group and significantly higher in high dose group than in normal and low dose groups. The concentrations of LD and ET-1 in model group were the highest. The concentrations of NO in model group and low dose group were significantly lower than those in high dose group and normal group.CONCLUSION: High dose Astragalus membranaeus has much better protective effect on hemorrhagic shockreperfusion injury of intestinal mucosa than low dose Astragalus membranaceus. The mechanism may be that Astragalus membranaceus can improve antioxidative effect and regulate NO/ET level during hemorrhagic reperfusion.