There are three layers of meninges on the surface of the human brain, one of which is wrapped around the surface of the brain like a spider’s web, under which there is a potential gap called the “subarachnoid space”. When blood flows into the subarachnoid space, we call it a “subarachnoid hemorrhage”. “The main manifestations of subarachnoid hemorrhage are: sudden onset of unbearable “splitting headache” or “death-like headache”, some people experience severe pain at the back of the neck and cannot lower their head. Some people experience severe pain in the back of the neck and cannot lower their heads; at the same time, the patient may vomit violently and become agitated; in severe cases, the patient may lose consciousness or even die. Subarachnoid hemorrhage is not a separate disease. The main causes of subarachnoid hemorrhage include intracranial aneurysm, cerebral arteriovenous malformation, smoker’s disease, and hematologic disease. Aneurysms rank third among cerebrovascular accidents, after cerebral thrombosis and cerebral hemorrhage, and are a disease that causes a high mortality and disability rate. About 80% of patients with subarachnoid hemorrhage are caused by ruptured aneurysm bleeding. According to authoritative scientific statistics, patients with subarachnoid hemorrhage in cerebrovascular disease have a mortality rate of more than 80% for those who experience rebleeding after the first episode is treated conservatively by internal medicine. Therefore, intracranial aneurysms and cerebral arteriovenous malformations are called “untimely bombs in the human body”. What should we do after suffering from subarachnoid hemorrhage? 1, when the patient appears the above symptoms, should immediately go to a regular large hospital with rich clinical experience in neurosurgery. 2.When conditions permit, whole brain angiography and related tests should be performed immediately to actively identify the cause of the hemorrhage.