The most common cause of subarachnoid hemorrhage is a cerebral aneurysm. Other causes can also cause subarachnoid hemorrhage, but they are relatively unlikely. A cerebral aneurysm is an abnormal bulge in the wall of a blood vessel in the brain, rather than a neoplastic condition. When the aneurysm wall is subjected to constant blood flow, the blood vessel wall gradually thins and ruptures, which can lead to subarachnoid hemorrhage. Other causes of aneurysms include cerebrovascular malformations, entrapment aneurysms, vasculitis, cerebral venous thrombosis, blood disorders (e.g., leukemia, coagulopathies, etc.), specific medication use (e.g., anticoagulants), neoplasms, and connective tissue disorders, among others. However, these causes are relatively less likely. When the symptoms of subarachnoid hemorrhage occur, the patient should consult the neurology department of the regular hospital in time to improve the relevant auxiliary examinations, to clarify the cause of the disease, and to guide further diagnosis and treatment.