Extracranial carotid stenosis is very closely related to cerebral ischemic diseases, especially stroke. About 30% of ischemic strokes are caused by extracranial carotid stenosis lesions, and the 2-year stroke rate can be as high as 26% in more than 70% of patients with symptomatic carotid stenosis. In stroke patients, the ratio of ischemic to hemorrhagic lesions is 4:1. The main cause of extracranial carotid stenosis is atherosclerosis. Epidemiological data show that 90% of carotid stenosis is due to atherosclerosis; the remaining 10% include fibromuscular dysplasia, arterial tortuosity, external compression, traumatic occlusion, intimal separation, inflammatory vasculopathy, radiation vasculitis, and amyloidosis. Extracranial carotid atherosclerotic lesions cause cerebral ischemic symptoms mainly through the following two mechanisms: 1. Embolization of intracranial arteries by plaque or thrombus shedding to form emboli. During the progression of carotid arteriosclerosis plaque, debris can be shed on the surface, and the debris itself can form embolus, which can flow to the distal intracranial vessels to form embolism. After the debris is shed, pro-thrombogenic substances such as collagen within the plaque are exposed, and the thrombus is formed and continuously shed leading to repeated embolization of the distal vessels. 2, stenosis causes distal cerebral tissue blood flow hypoperfusion. Carotid ultrasound is safe, easy and low cost, and is mostly used for screening and follow-up of extracranial carotid stenosis lesions. Digital subtraction angiography is still the “gold standard” for the diagnosis of carotid artery stenosis. Currently, the main goal of treatment for carotid artery stenosis is to improve cerebral blood supply, correct or alleviate symptoms of cerebral ischemia, and prevent the occurrence of stroke. Treatment methods include pharmacological, surgical and interventional treatments. Clinical studies have confirmed that carotid endarterectomy is more effective than pharmacological treatment for patients with symptomatic moderate stenosis and asymptomatic severe stenosis; in recent years, carotid stenting has been developed more rapidly because of its minimally invasive, safe, simple procedure, fast recovery and wide indications.