Abstract: Objective: To study the diagnostic effect of SAH(CT) in the diagnosis of primary subarachnoid hemorrhage(CTA) and to evaluate the effect of serum S-100 protein on brain damage and cerebral vasospasm in SAH patients. Methods: patients with CTA from 2013 April 2014 march in our hospital, according to Glasgow Coma Scale(GCS) coma score and hunt Hess grade divided into different groups, they were detected by 256 slice spiral CT head CTA examination and serum S-100 B protein levels. Results: In 77 patients with SAH by CT sports a CTA examination 59 aneurysm. GCS score 3~8 points of patients admitted to hospital after 1 d, 7 d S-100 B protein levels were(1.94 ±0.31) μg/L respectively,(1.93 ±0.28) μg/L was significantly higher than patients with GCS score 9~12 points 1d, d after admission S-100 B protein levels(1.13 ±0.21) of μg/L,(1.09 ±0.19) μg/L and GCS score 13~15 points, 1 d, 7 d after admission in patients with S-100 B protein levels(0.54 ±0.09) of μg/L, μg/L(0.52 ±0.06), statistically significant difference(P<0.05). Hunt and Hess grade I^II patients admitted to hospital after 1 d, 7 d S-100 B protein levels were(0.68 ±0.12) μg/L,(0.64 ±0.11) of μg/L significantly lower than Hunt-Hess level III patients admitted to hospital after 1 d, 7 d S~100B protein levels(1.15 ±0.18) μg/L,(0.98 ±0.12) μg/L and Hunt-Hess level IV patients admitted to hospital after 1 d, 7 d S~100B protein levels(2.08 ±0.25) of μg/L,(1.99 ±0.23) μg/L, statistically significant difference(P<0.05). Conclusion: 256 slice spiral CT head and neck CTA scan can be effective response to the peripheral vascular three-dimensional structure of patients with SAH, the SAH patients with S-100 B protein level detection, can effectively evaluate the degree of brain damage and vascular spasm in SAH patients.