Objective: To study the regulation effects and mechanisms of Pigment epithelium-derived factor on Alzheimers disease.Methods: To observe β-amyloid(Aβ)depositions in the hippocampus of wild type and PEDF-/-mice.To choose SAMR1 as control,SAM8 as model dementia mice,then devided SAM8 mice into model group and medicine group.Medicine group would be given PEDF every day for a month,while the control group and model group would be given normal saline at the same time.Then,five groups of mice would all accept Morris water maze behavioral experiments in order to test whether the dementia model was successed and whether the PEDF could improve spatial learning and memory of Alzheimers disease model mice by hidden platform experiments and Explore experiments.To evaluate the efficacy and mechanism of PEDF,the mice were tested by western blot,immunohistochemistry methods,etc.Result: PEDF treatment significantly attenuated SAM8 abnormalities in cognition and brain histological morphology.Compared with wild type mice,Aβ deposition increased in the brain of PEDF knock out mice.Conclusion: PEDF can ameliorate the Alzheimers disease and may show significant effects in the treatment of AD.The therapeutic mechanism may be related to a number of processes modulated by PEDF,mainly through promotion of neuroprotection and neurogenesis,with additional promotion of anti-oxidation,protein degradation,etc.