Ischemic stroke is a common and frequent disease in humans, and the annual incidence of ischemic stroke in China is 120-180/100,000, and the annual morbidity and mortality rate is 80-120/100,000, and arterial stenosis is one of the main factors. Atherosclerosis is the basic cause of narrowing and occlusion of the lumen of the main or branch cerebral arteries, which causes a reduction in local blood flow or interruption of blood supply to the brain, resulting in impaired cerebral energy metabolism and eventually leading to cerebral infarction. Atherosclerosis of the large intracranial vessels is the main cause of ischemic stroke. Cerebral atherosclerosis mainly invades large and middle cerebral arteries with a diameter >500 μm or more, and the lesions of major cerebral arteries around Willi’s ring are severe in Orientals and are closely related to hypertension. In recent years, it has been found that the major cerebral arteries account for 20%-30% of the entire vascular resistance in normal times, and up to 50% in chronic hypertension, which inevitably leads to atherosclerotic damage of the major cerebral arteries in long-term hypertension. In foreign studies, Bauer et al. were the first to find racial differences in the distribution of atherosclerosis in an angiographic study in the early 1960s. In recent decades, numerous studies, including angiography and pathology, have confirmed that extracranial stenosis is more common in Europeans, whereas intracranial stenosis is more common in Asians, blacks, and Hispanics. In 1990, Feldmann reported a 24% frequency of middle cerebral artery trunk stenosis in 24 Chinese patients with transient ischemic attack or stroke at the New England Medical Center, compared with 14% in age- and sex-matched white patients. These studies suggest that Asian stroke patients (Japanese and Chinese) have a higher incidence of intracranial vasculopathy than white patients in the United States and Europe. The analysis of TCD, carotid ultrasound and DSA results in 96 patients with transient cerebral hypoperfusion at Peking Union Medical College Hospital showed that 51% of patients had intracranial stenosis or occlusion and 19% had extracranial vascular lesions. The middle cerebral artery was most frequently involved in 66% of the cases. A study of 66 acute stroke patients with TCD at the Chinese University of Hong Kong found similar results, with a frequency of 33% for intracranial vascular lesions and 6% for extracranial vascular lesions, with stenosis of the middle cerebral artery being the predominant intracranial vascular lesion. Examination of 705 consecutive Chinese patients with acute stroke admitted to the Prince of Wales Hospital of the Chinese University of Hong Kong showed that 345 (49%) had large arterial occlusive lesions, of which 258 (37%) had only intracranial vascular lesions, 71 (10%) had both intracranial and extracranial vascular lesions, and 16 (2.3%) had only extracranial vascular lesions. The distribution of intracranial vascular stenosis was in the following order: middle cerebral artery (73.3%), vertebrobasilar artery (40.3%), and anterior cerebral artery (35.9%). These findings suggest that intracranial vascular lesions are the most common in symptomatic patients. In a study of an asymptomatic population, the Peking Union Medical College Hospital investigated 1574 healthy workers and retirees over 40 years of age from four different regions of Beijing by TCD, and the results showed that 47 (2.9%) had vascular lesions, with the middle cerebral artery being the most common intracranial artery, accounting for approximately 70% of all stenoses [8]. Subsequently, the Chinese University of Hong Kong and Peking Union Medical College Hospital jointly investigated the incidence of intracranial cerebral vascular stenosis in a village in Henan, China, examined 507 people, and found that the frequency of intracranial vascular stenosis in people over 40 years of age was 7%. Similar findings were found in 3000 asymptomatic patients from 5 hospitals in Hong Kong. Conclusion: Intracranial stenosis, especially middle cerebral artery stenosis, is the predominant vascular pathology in Chinese patients. Risk factors for intracranial stenosis include hypertension, diabetes mellitus, family history of stroke, and history of heart disease, and the coexistence of several risk factors can significantly increase the risk of stenosis.