Alzheimer disease（ AD） is the most common senile dementia， but the cause of the disease is still unclear， and lack of effective treatment. In recent years， studies have shown that neurometabolic problems may be the root cause of AD， and low glucose metabolism in the brain is an important feature of the early AD， while the ketogenic diet with high fat and low carbohydrate provides the possibility to solve these metabolic problems. Current studies have shown that ketogenic diet intervention in the early stage of AD can improve cognition， and its mechanism may be related to improving energy metabolism， reducing the level of pathological markers and neurotoxicity， and regulating intestinal flora. This paper gives a summary of the related progress