Abstract: ob＜x＞jective: To investigate the clinical value of transcranial Doppler (TCD) in the perioperative period of carotid endarterectomy (CEA). Methods: 32 patients treated with CEA ,admitted to our hospital from March 2015 to December 2019,were chosen. Preoperative,intraoperative and postoperative TCD evaluations on these patients were performed. CT and MRI were used to determine whether there was cerebral hemorrhage or ischemia. Results: preoperative evaluation: 17 of 23 patients with severe carotid stenosis (73.9%) had the communicating branch.6 of 9 patients with moderate carotid stenosis (66.7%)had the communicating branch . Intraoperative monitoring: The mean velocity (VM) of MCA before temporary obstruction was lower than that before anesthesia (P < 0.05).The MCA VM after temporary obstruction was lower than that before anesthesia and before temporary obstruction (P < 0.05). The MCA VM after relieving temporary obstruction increased c ompared with that before anesthesia and before temporary obstruction (P < 0.05) .The invasive blood pressure after temporary obstruction was higher than that before temporary obstruction.The invasive blood pressure after relieving temporary obstruction wa s lower than that after temporary obstruction and before temporary obstruction(P < 0.05) .The MCA VM of 10 patients was lower than 70% of the basic value, and the MCA VM of 3 patients increased more than 100% after reliev ing temporary obstruction. Postoperative evaluation and follow-up: The MCA VM and PI of the operative side increased (P < 0.05), and the communicating artery was closed. One patient had headache and three patient s had restlessness. Conclusion: During CEA, TCD can accurately evaluate the opening of intracranial communicating artery before operation, real-time monitor the changes of cerebral hemodynamics during operation, guide to regulate the blood pressure timely, prevent the occurrence of cerebral ischemia and over perfusion in perioperative period, evaluate the recovery of cerebral blood flow and the closure of collateral circulation after operation, so as to improve the success rate of surgery significantly.