Aneurysms were not detected by angiography in about 15% of SAH patients, of which 38% were identified as NAPSAH.In 1991 Rinkel et al. scanned patients with subarachnoid hemorrhage by CT and MR and described the standard definition of NAPSAH:The center of the hemorrhage is immediately anterior to the midbrain with or without hemorrhagic extension toward the base of the circumflex pools, does not completely fills the anterior portion of the longitudinal fissure pool, generally does not extend laterally into the lateral fissure pool, and there is no obvious intracranial hematoma or intraventricular hemorrhage. It has also been described as having no clear etiology on transcerebral angiography. At present, the factors of negative NAPSAH angiography are not clear, domestic and foreign scholars consider more possible etiologies, related to venous hemorrhage, rupture of arterial perforating branches, cervical dural arteriovenous leakage, cavernous hemangioma of the brainstem, dilatation of the capillaries, occult intracranial arteriovenous malformations, and secondary hemorrhage after occlusion of small perforating branches, but also including low-pressure hemorrhage in the wall of the basilar artery, and occlusion of the veins and venous sinuses. Factors, some scholars for subarachnoid hemorrhage patients angiography negative factors that: basilar vein or its branch variant; aneurysm thrombosis or aneurysm of the stem is too narrow; basilar artery perforating branch of small aneurysm rupture failed to clearly show and so on and easy to miss; thalamus perforating artery rupture, dura arteriovenous fistula, and so on. NAPSAH onset of age is relatively young, the average age of about 50 years old, other scholars say, 40 ~ 60 years old group NAPSAH incidence rate is higher, in recent years, with the change of dietary structure and the accelerated pace of life there is a tendency to rejuvenation. Risk factors related to hypertension, diabetes mellitus, smoking, physical activity, oral contraceptives and emotional excitement, etc., part of the patients in the rest of the onset, the etiology of hidden. NAPSAH and other causes of SAH is similar, often manifested as a sudden headache with or without nausea, vomiting, and photophobia, a small number of patients may be manifested in the lower back and legs radiating pain, etc., but less likely to have intracranial vascularization, but less likely to have intracranial vascularization. The clinical symptoms of NAPSAH are less severe than those of aneurysmal SAH, and the headache is mostly tolerable, with mild to moderate swelling and pain, mostly in the temporal or posterior occipital region, with no consciousness disorder, focal neurological deficits, or epileptic seizures. Compared with SAH due to aneurysm rupture, complications such as rebleeding, cerebral vasospasm, and hydrocephalus are rare in NAPSAH. Cerebral vasospasm was not shown in this group of cases. Foreign scholars meta-analyzed the relevant literature from 1985 to 1999, and the longest follow-up time of the 290 patients with NAPSAH reported was 8 years, and no reports of rebleeding, cerebral vasospasm and other related reports were found. Cranial CT examination is more sensitive for the acute stage of hemorrhage, and can be the first choice of examination for NAPSAH and further CTA or MRV examination, CT shows that NAPSAH hemorrhage is mainly confined to the peripheral pool of the midbrain. In this group of cases, it was found that NAPSAH often involved the anterior bridge pool and the ring pool, and some were the only site of hemorrhage; tetralogy of fallot pool hemorrhage is also a common site of NAPSAH, and some foreign scholars pointed out that NAPSAH in the tetralogy of fallot can be considered to be negative in the first time of CTA examination, and at least 2 times of cerebral angiography can be considered again to rule out the possibility of aneurysm. It is agreed at home and abroad that the type of original SAH may change within a certain time frame due to the absorption and redistribution of blood in the subarachnoid space. In the clinical observation of 21 patients collected in this paper, the vast majority of patients with NAPSAH reviewed head CT after 1 week and found that the original SAH had been basically absorbed, and in some patients, the blood had been completely absorbed by reviewing head CT at 10 days. Therefore, it is recommended that early cranial CT examination is very important for the diagnosis of NAPSAH.NAPSAH needs to improve the angiographic examination in the clinic. Although DSA is highly regarded in the diagnosis of SAH, some scholars believe that CTA and DSA have the same sensitivity and accuracy, and are safer and easier for patients to accept, and CTA-negative patients do not need to have another DSA examination. I still recommend the need for DSA examination, and even need 1 week to review, increase the detection rate of aneurysm, in order to clarify the etiology can not be ignored DSA is still the gold standard. Following the conventional treatment of SAH, the treatment strategy is changed to some extent, only need to dehydrate the patient to reduce the cranial pressure, hemostasis, symptomatic and prevent cerebral vasospasm treatment and close observation of the condition. It is not necessary to strictly enforce bed rest and restrict activities, but still need to actively control blood pressure and monitor electrolytes. The patient’s condition recovers faster, a few patients show easy fatigue and anxiety, which is considered to be related to the psychological burden.