To explore the effect of Rannasangpei on the SOD ,CAT and MDA in the brain tissues of rats with permanent middle cerebral artery occlusion (PMCAO), and to study its cerebral protective mechanism.Methods：SD rats were made into local cerebral ischemic models with the method of permanent middle artery occlusion. The effects of Rannasangpei on the volume of cerebral infarction in rats and the changes of SOD, CAT and MDA contents in their brain tissues were observed．Results：The infarct volumes of rats in two Rannasangpei intervention groups were obviously decreased compared with the PMCAO model group(P<0.01 orP<0.05);compared with the PMCAO model group, the SOD and CAT contents in brain tissues of the rats in the high and low dose Rannasangpei groups were all significantly increased, the MDA contents were decreased in different degrees(P<0.01).Conclusion：Rannasangpei has significant protective effect on cerebral ischemic injury in rats, and its protective mechanism may come from effectively enhancing ability of the endogenous antioxidant enzyme to scavenge the free radicals, and relieving lipid peroxidation damage of brain tissue.