Alzheimer disease（ AD） is the main cause of dementia. At present， there is no effective treatment plan. The development of new drugs for AD treatment has also been persistently unsuccessful. Therefore， it is of great significance to emphasize AD prevention. In recent years， with the rapid development of biomarkers for the diagnosis of AD， early diagnosis of AD has become increasingly accurate. In addition， there is growing evidence that AD， like other chronic diseases， has many preventable risk factors， and early intervention with these risk factors can help delay or prevent AD. This article mainly discusses the risk factors and pathogenic mechanism of AD， from primary prevention based on identifying and reducing risk factors， to secondary prevention based on early detection of AD pathophysiological characteristics， early diagnosis in the early preclinical stage， and early intervention. The aim of this article is to call for awareness and attention to AD prevention and promote scientific prevention and control.