Learning-memory deficit in different ages of APP(amyloid precursor protein)transgenic mice was investigated and the protective effects of epimedium flavonoids(EF)were observed on development of β-amyloid in brain of 10 months old of APP transgenic mice.The mice of drug treated group were administered introgastrically by EF(at doses 0.03 and 0.1 g·kg-1/d)from 4 to 10 months old.The mice of normal group and negative transgene group were administered of distilled water by the same way.The learning-memory ability was measured by applying Morris water maze(MWM)and object recognition test(ORT).The expression of APP and β-secretase(BACE)in hippocampus and cortex were detected by immunohistochemistry and Western Blot respectively.The content of insoluble β-amyloid 1-42(Aβ1-42)in hippocampus were measured by ELISA Assay Kit.The results show that learning-memory deficit was detected in 4 months old Tg mice.The learning-memory deficit was aggravated in 10 months old Tg mice.Their escape latency and swimming distance in MWM was prolonged,and the discrimination index decreased in ORT.Epimedium flavonoids improved learning-memory impairment of 10 months old Tg mice in MWM as well as in ORT,and decreased the expression of APP,BACE and the content of Aβ1-42 in brains.These results suggest that different ages of Tg mice could mimic pathological proceeding of AD.Epimedium flavonoids may have a promising application prospect in treatment of AD.