Subarachnoid hemorrhage (SAH) is an acute hemorrhagic cerebrovascular disease in which blood flows directly into the subarachnoid space due to rupture of blood vessels at the base of the brain or on the surface of the brain and spinal cord from a variety of etiologies. Common causes are cerebral artery malformations, aneurysms, and blood disorders. Patients present with severe headache, neck straightening, self-perceived “tear-like” or “electric shock-like” headache, often accompanied by nausea, vomiting, and in severe cases, convulsions, unconsciousness, and even respiratory and cardiac arrest. About 10-15% of patients die before reaching the hospital. The diagnosis can be made by cranial CT, which shows high density in the subarachnoid space; CT may not be diagnostic when the amount of bleeding is small, and sometimes lumbar puncture is needed to confirm the diagnosis. Cerebral angiography (DSA): It is the most valuable method to diagnose intracranial aneurysm, with a positive rate of 95%, and can clearly show the location, size, relationship with the aneurysm-carrying artery, and the presence of vasospasm of the aneurysm. When conditions are available and the condition permits, whole brain DSA should be performed as soon as possible to determine the cause of bleeding, decide the treatment method and judge the prognosis. However, since angiography can aggravate neurological damage, such as cerebral ischemia and re-rupture of aneurysm, the timing of angiography should avoid the peak period of cerebral vasospasm and re-bleeding, i.e. within 3 days or 3 weeks after bleeding.