Objective To investigate the pathogenesis treatment and prognosis of cerebral vasospasm due to subarachnoid hemorrhage. Method In this research ,we studied cerebral vasospasm group(n=42)and controlled group(n=50)without cerebral vasospasm due to subarachnoid hemorrhage, used Nimodipine to treat CVS,meanwhile, observed the curative effect and estimated the prognosis. Results There is no marked difference in age and sex between two groups(P0.05). Most patient with CVS were occurred within 2 weeks. There was 34 cases of 42 cases whose cerebral ischemic symptom was disappeared and 8 cases were death. The mortality of CVS group is higher than controlled group(P0.05). Conclusion Cerebral vasospasm due to subarachnoid hemorrhage could mostly be reversed by early detection, exactly diagnosis and treatment.