Objective To compare the effects of different time preconditioning of carotid endarterectomy（CEA）on postoperative stress response and neurological function．Methods From December 2019 to December 2022,74 patients with carotid stenosis（CS）who were selected for CEA treatment in our hospital were retrospectively collected and divided into two groups according to the time of remote ischemic preconditioning（RIPC）,including 37 cases in group A（preconditioning at 1 hour before surgery）and 37 cases in group B（preconditioning at 24 hours before surgery）．The changes of sympathetic response indexes [systolic blood pressure（SBP）,heart rate（HR）,diastolic blood pressure（DBP）] in the 2 groups at 1 d before surgery,after the anesthesia induction,and at the time of skin incision before and after surgery,and the scores of the Mini-Mental State Examination（MMSE）,stress indexes [norepinephrine（NE）,interleukin-6（IL-6）,cortisol（Cor）],and neurological function indexes [brain-derived neurotrophic factor（BDNF）,neuron specific enolase（NSE）,central nervous specific protein（S-100β）]．Results Compared with group A,the levels of SBP,HR and DBP in group B after anesthesia induction were higher,and the levels of SBP,HR and DBP were lower during skin resection（P<0.05）．Compared with group A,group B had higher MMSE scores at 7 and 30 days after surgery（P<0.05）．The serum levels of NE,Cor and IL-6 in the 2 groups were increased 12 h and 24 h after surgery compared with 1 day before surgery（P<0.05）,but there was no significant difference between the 2 groups（P>0.05）．Compared with group A,serum S-100β and NSE levels in group B were lower at 12 h and 24 h after surgery,and serum BDNF level was higher in group B（P<0.05）．Conclusions The administration of RIPC before CEA can reduce brain injury and play a protective role in brain．However,compared with the administration of RIPC 1 h before surgery,the administration of RIPC 24 h before surgery is more conducive to maintaining hemodynamic stability,promoting cognitive function and prognostic recovery．