The three main causes of thrombosis include vascular wall lesions, blood component changes and blood flow changes: 1, In addition, acquired factors include hypertension, hyperlipidemia, diabetes, smoking, etc., which are its risk factors. Another reason is that various cerebral arteritis can also cause the lesion of blood vessel wall, congenital abnormal development of blood vessels, amyloid lesion of blood vessels, etc., which can also cause the change of blood vessel wall and form one of the factors of thrombosis. 2, the change of blood composition, blood composition changes mainly include, for example, true erythrocytosis, thrombocytosis, etc., so that the blood becomes viscous, and the blood coagulation is increased, that is, in a hypercoagulable state. 3, hemodynamic changes, blood pressure abnormalities, including high or low blood pressure, heart dysfunction, such as atrial fibrillation cardiac insufficiency, cerebral vasospasm, congenital arterial stenosis, etc., are all factors that lead to thrombosis.