As population ageing is intensifying globally, the problem of cognitive disorders such as Alzheimer′s disease and other related dementias due to ageing is becoming more pronounced. These problems not only seriously affect the health and quality of life of older people, but also bring a heavy burden to society. More and more studies have found that, in addition to common risk factors such as age, gender and various chronic diseases, lipid levels play an increasingly important predictive role in identifying cognitive dysfunction and preventing dementia. In this paper, we reviewed the literature on the correlation between blood lipid levels and cognitive impairment, and focused on the effect of lipid levels on cognitive impairment, their action mechanism, and the traditional and non-traditional relationship between them, with a view to providing new ideas and references for the clinical diagnosis and prevention of cognitive impairment.