Reactive oxygen species are important factors,which directly or indirectly involve in the process of cerebral ischemia and reperfusion injury. They are not only regulated by the balance between prooxidant and antioxidant enzymes in brain,but also participate in the various molecular signal pathway in cells. Therefore,they play an important role in the course of neuronal death events. In recent years,transgenic and gene-knockout mice have been widely used in research of the enzymes which influence the formation and elimination of reactive oxygen species,And they also are utilized in the study of the proteins which mediate a variety of cell death and apoptosisl. The animals provide necessary conditions for researchers to conduct the foundamental and applied studies on treatment of cerebral ischemia or reperfusion injury.