Abstract: OBJECTIVE To investigate the protection mechanism of fusion protein PTD-SOD on damaged cerebral tissues by studying the effect of PTD-SOD on cerebral ischemia-reperfusion(CIR) of rats. METHODS To establish middle cerebral artery occlusion models with middle cerebral artery thread embolism method for two-hour ischemia and twenty-four-hour reperfusion, to observe variations of areas of cerebral infarction by TTC staining method, to measure changes/variations of indices of anti-oxidative system and oxidative levels of cerebral homogenate of rats, and the damage situation of cerebral cells were tested by paraffin sections and HE staining. RESULTS Compared with model groups, the areas of cerebral infarction of administration groups were much smaller, the levels of antioxidative indices of cerebral tissuse, such as SOD, GSH-PX and CAT, were significantly increased, while the level of MDA was significantly decreased. At the same time, HE staining showed the damage situation of cerebral cells of administrtion groups were less than cerebral cells of model groups. CONCLUSION Oral administration of PTD-SOD is able to improve levels of anti free radical effect on cerebral tissuse, as well as lessen cerebral infarction and decrease the damage situation of cerebral cells of ischemia reperfusion rats.