At present, cerebral vasospasm (cVS) is the main cause of delayed cerebral infarction (DCI), which leads to high disability and mortality rate after aneurysmal subarachnoid hemorrhage. As a consequence, the key of reducing DCI is to prevent cVS. But unfortunately, despite years of efforts, the prevention and treatment of cVS is still a major clinical dilemma and various ways of treatment are still being explored. Recent studies have shown that stellate ganglion block (SGB) can dilate cerebral vessels and alleviate the impact of existing cVS. However, there is no study to evaluate the effect of early application of SGB on the improvement and prevention of cVS after aSAH.