To explore the effect of remote ischemic conditioning (RIC) on cerebral blood flow in patients with aneurysmal subarachnoid hemorrhage (aSAH). Methods: Included in this study were 24 aSAH patients consecutively admitted to the Intensive Care Unit of the Department of Neurosurgery at Xuanwu Hospital from November 2017 to May 2018. All patients underwent aneurysm clipping and embolization treatment within 72 hours of aSAH and received RIC 5 times within 7 days after treatment. Before and after RIC intervention, transcranial doppler (TCD) was used to evaluate cerebral blood flow in the anterior circulation, including that of the bilateral anterior cerebral arteries (ACA), bilateral middle cerebral arteries (MCA), and the ipsilateral MCA/ internal carotid artery (ICA) terminal section flow velocity ratio (ratio). The posterior circulation blood flow was also evaluated, including that at the bilateral posterior cerebral arteries (PCA), bilateral vertebral arteries (VA), and basilar artery (BA). Head CT or MRI recheck was performed after RIC intervention to evaluate the fresh infarctions. Results: Compared to data before RIC intervention, cerebral blood flow after intervention at the R-MCA, L-ACA, and R-ratio of the anterior circulation were increased (all P<0.05), with this increase being less than 20% , and the remaining parameters showed no significant difference (P>0.05). After RIC intervention, blood flow at the L-VA and BA of the posterior circulation were increased compared to those before intervention (all P0.05). Neither CT nor MRI showed fresh cerebral infarction after RIC intervention. Conclusion: RIC had no obvious effect on cerebral blood flow in patients with aneurysmal subarachnoid hemorrhage and did not trigger fresh cerebral infarctions. This study confirms the preliminary safety of RIC.