Abstract: Objective:To observe the changes in anti-oxidative ability of brain in aging mice induced by D-galactose.（Methods:）Mice were divided into two groups : normal control group and senile model group.Mice in senile model group were injected with D-galactose 150mg kg^-1by intra peritoneum,while the controls were given normal saline per day.Eight weeks later,mice were killed to make electron microscope specimens and to observe the changes of anti-oxidative ability of brain.Results:In senile model group,the activities of SOD and NOS decreased,the levels of MDA and lipofuscin increased and the NO level decreased.Conclusions:The Anti-oxidative ability of brain in D-galactose induced senile mice decreased.