This paper briefly describes the mechanism of neurochemical changes in AD,the roles of the epigenetics,the regulation of gene expression and the mechanism of epigenetics in SAD.On the basis of the basic study on the AD during the decades,researchers initially revealed the mystery of the unfathomable neurochemical changes attack on AD.Especially in recentyears,researchers summarized the abnormal protein expression on SAD into epigenetics disease.This achievement helps researchers point out the new and strategic direction on AD pathogenesis,prevention and control mechanism.With the understanding of biological characteristics of epigenetics,AD needs to be studied in depth.