Objective To investigate the role of atorvastatin calcium in cerebral vasospasm (CVS) after aneurismal subarachnoid hemorrhage (aSAH) and related mechanisms.Methods A total of 62 patients with aSAH who were admitted from March 2013 to November 2015 were enrolled and randomly divided into study group (33 patients) and control group (29 patients). The patients in the control group were given conventional treatment, and those in the study group were given atorvastatin calcium (20 mg/qn for 14 consecutive days) in addition to the conventional treatment. The mean blood flow velocity of the middle cerebral artery (VMCA) and serum levels of endothelin-1 (ET-1) and nitric oxide (NO) were measured at 1, 3, 7, and 14 days after onset. Meanwhile, the incidence rates of CVS, late-onset cerebral infarction, and recurrence of bleeding and Modified Rankin Scale (mRS) score were compared between the two groups.Results At 7 and 14 days after onset, the study group had significantly lower VMCA and serum level of ET-1 than the control group (P<0.05). At 3, 7, and 14 days after onset, the study group had a significantly higher level of NO than the control group (P<0.05). Compared with the control group, the study group showed a significantly lower incidence rate of CVS (36.36% vs. 65.52%, P<0.05) and a significantly higher proportion of patients with an mRS score of ≤2 (75.76% vs. 44.83%, P<0.05). There were no significant differences in the incidence rates of late-onset cerebral infarction and recurrence of bleeding between the two groups (P>0.05).Conclusions Atorvastatin calcium can reduce the occurrence of CVS and promote the recovery of neurological function after subarachnoid hemorrhage, and its mechanisms may be related to the improvement in endothelial vasomotor function.