Objective To assess the risk of hyperperfusion induced intracranial hemorrhage (HICH) after carotid artery stenting (CAS) in patients with symptomatic severe carotid stenosis.Methods From June 2009 to June 2015,the clinical data of 210 patients with symptomatic severe carotid stenosis (70％-99％) treated with CAS at Department of Neurosurgery,Changhai Hospital,the Second Military Medical University,were analyzed retrospectively.Seven of them (3.3 ％) developed HICH after operation.The relationship between the clinical baseline and imaging characteristics and HICH were assessed.All patients received the evaluation of cerebral CT perfusion examination.The time to peak (TTP) index of cerebral blood flow was defined as the TTP ratio of the affected and contralateral sides,t test was used to conduct the comparison of measurement data,and Poisson test was used to conduct the comparison of the enumeration data.Results There was significant difference in the TTP index between the HICH group and non-HICH group (1.15 ± 0.10 vs.1.30 ± 0.15,t =4.461,P ＜ 0.01).The receiver operating characteristic (ROC)curve analysis results suggested that the TTP index ＞ 1.22 could be used as a risk factor for predicting HICH (sensitivity 100％,specificity 75.9％).Conclusion Under the condition of prompting the preoperative TTP index ＞ 1.22,the risk of HICH may be higher after CAS in patients with severe carotid stenosis.