The stenosis of the circumflex segment of the posterior cerebral artery refers to the stenosis of the posterior cerebral artery from the horizontal segment to the back of the upper course to stop at the tetralogy of Fallot, mostly caused by atherosclerosis, and is categorized into mild stenosis, moderate stenosis and severe stenosis, which is the cause of cerebral infarction, and the treatment methods include medication and surgical treatment. 1. Posterior cerebral artery is the main blood vessel supplying blood to the hindbrain, which is mainly responsible for supplying brain tissues such as thalamus, medial temporal lobe and occipital lobe, etc. Circumferential pool segment generally refers to the portion of the posterior cerebral artery that is issued from basilar artery and then turns and travels upward to the posterior through the horizontal segment and stops at tetralogy of fallot pool. 2. Posterior cerebral artery stenosis is mostly caused by atherosclerosis. According to the degree of stenosis, it is categorized into mild stenosis (<50%), moderate stenosis (50%-70%), and severe stenosis (>70%), which is an important etiological factor leading to cerebral infarction in the posterior circulation. 3. Pharmacological treatment is the basic treatment, and anti-platelet drugs such as aspirin and plaque stabilizing drugs such as atorvastatin are recommended; interventional surgery can be considered for severe stenosis. If stenosis of the circumflex segment of the posterior cerebral artery is found, it is recommended to seek medical treatment in time to prevent the occurrence of cerebral infarction.