Stenosis of the large intracranial arteries and extracranial carotid arteries is a common cause of ischemic stroke, and the proportion of intracranial stenosis-especially stenosis of the middle cerebral artery-is highest among young and middle-aged patients in China. The ideal treatment for intracranial stenosis is inconclusive and mainly includes pharmacological treatment, interventional treatment, and vascular bypass therapy. Interventional treatment or vascular bypass surgery can be used for patients who fail to respond to medical treatment. In recent years, although special intracranial vascular stents have been produced, they are expensive and have been used in clinical practice for a short period of time, and their long-term efficacy needs to be further evaluated. Intracranial-extracranial bypass for ischemic cerebrovascular disease is a well-established technical tool that is described as a “new weapon” because it was already available in the 1970s, but it has been neglected because of the shortcomings of previous studies and designs. With recent re-evaluations, bypass surgery has been gaining encouraging results in the neurosurgical community. What types of patients are candidates for bypass surgery? There are two types of ischemic diseases: transient ischemic attack (TIA) and cerebral infarction. The best indication for bypass surgery is recurrent TIA that has not been treated with medical therapy to prevent stroke; the purpose of bypass surgery for cerebral infarction is to save the brain tissue in the hemispheric zone to improve and reduce the damage to the ischemic brain tissue. In addition, bypass surgery is also suitable for patients with Moyamoya disease (smog) and giant intracranial aneurysms. What are the advantages of bypass surgery? The conservative medical treatment is long, slow and recurrent. Bypass surgery improves the blood supply to the ischemic brain tissues directly through revascularization, which can bring better prognosis for patients with poor results of conservative medical treatment; vascular interventional stent placement is expensive and a new technology introduced in recent years. The cost is relatively low, the risk of surgery is low, and no artificial material is implanted. How is bypass surgery performed? There are two main types of intracranial-extracranial vascular bypass for ischemic cerebrovascular disease. One is low-flow (15-25 ml/min) bypass, which uses direct anastomosis between the branches of superficial temporal artery and intracranial vessels to treat ischemic cerebrovascular disease. This kind of low-flow intracranial-extracranial artery bypass cannot meet the normal local blood supply to the brain (50-55 ml/100g/min), and the opening rate of the vessels is not high after the anastomosis bypass of the last small artery, so the surgical effect is poor. Another surgical procedure is high-flow (70-140 ml/min) bypass, which is performed using the radial artery or saphenous vein. This high-flow cerebral revascularization technique has good therapeutic results and requires not only the selection of a suitable supply vessel, but also superior surgical skills that can anastomose the graft to the deep main brain supply artery. All this requires not only the support of highly sophisticated equipment, but also a highly skilled surgical team with close multidisciplinary collaboration. Our hospital has DSA (Digital Subtraction Angiography System), Philips 3.0 TMR, spiral CT, high magnification German imported Lycra microscope, intraoperative EEG monitoring, intraoperative Doppler, imported microscopic anastomosis instruments, etc. We have been the first in the province to perform hundreds of cases of this surgery, which has brought gospel to patients with cerebral ischemic diseases.