Brain blood supply is rich, metabolism is vigorous, oxygen consumption is large, brain tissue oxygen consumption accounts for 20%-30% of the whole body’s oxygen consumption, and its energy is mainly derived from sugar aerobic metabolism, almost no energy reserves, so brain tissue is very sensitive to ischemia and hypoxia, low partial pressure of oxygen or blood flow significantly decreased will damage brain function, blocking blood flow significantly decreased will damage brain function, easy to occur cerebral infarction. In the center of cerebral infarction, there is an ischemic semi-dark zone around the necrotic area, within which there is still collateral circulation, which can obtain part of the blood supply, so there are still a large number of neurons that can be survived, such as the rapid restoration of the cerebral blood supply, the damage is reversible, and the neuronal cells can be survived, but the prerequisites must be in the effective reperfusion time window. Currently, the time window for ultra-early treatment of cerebral ischemia is generally set at 6 hours, and it is critical to treat acute cerebral infarction by attending the clinic within 6 hours of the onset of the disease, so as to restore the function of the reversibly damaged neurons in the ischemic semidomain band. The proposal of ischemic semi-dark band and reperfusion injury has updated the clinical treatment concept of acute cerebrovascular disease, i.e., the key to ultra-early treatment is to rescue the ischemic semi-dark band and to take cerebral protective measures to reduce reperfusion injury. Therefore, when the patient has symptoms such as unfavorable limb movement, numbness, crooked mouth, poor speech, etc., he must be highly alert and not be paralyzed, but go to the hospital as soon as possible to get the best treatment time.