Increased serum homocysteine level is a risk factor for vascular endothelial dysfunction. It has a similar pathological process to the endothelial function damage of large arteries and small arteries. Compared with large artery endothelial cells， small artery endothelial cells were more sensitive to serum homocysteine. Therefore， it is important to study the correlation between cerebral small vessel disease and serum homocysteine level. Many studies in China and abroad have confirmed that the level of homocysteine is related to the imaging subtypes of cerebral small vessel disease， cognitive dysfunction， and the occurrence and development of dementia. This article reviews the relationship between cerebral small vessel disease and serum homocysteine level， which is of great significance to the clinical diagnosis and treatment of cerebral small vessel disease.