Elevated homocysteine indicates a decrease in the body’s methylation and antioxidant capacity and an increased risk of cardiovascular and cerebrovascular diseases. The geometric mean value of blood homocysteine in adults in China is 13-14 μmol/L. Elevated homocysteine is known as hyperhomocysteinemia, which is an independent risk factor or an important risk factor for a variety of chronic diseases, such as stroke and cardiovascular diseases. Risk factors for elevated homocysteine include genetic factors, nutritional factors and lifestyle, age and gender, diseases and medications, such as genetic mutations, alcohol and smoking, low folic acid intake, aging, hypothyroidism, diuretics, and so on. Elevated homocysteine is an independent risk factor for stroke and also predicts the risk of Alzheimer’s disease. It has also been found to be strongly associated with a variety of diseases including ischemic heart disease, hypertension, diabetic complications, chronic kidney disease, bone fractures, men’s diseases, tumors, and liver disease. When homocysteine is high, it is recommended to consult a doctor in time to identify the cause of the disease. Clinical examination of blood homocysteine and folate metabolism genes can be done to identify the cause of the disease, and lifestyle and nutritional interventions can be given according to the doctor’s instructions.