Objective To investigate the predictive value of hypoperfusion intensity ratio (HIR) on the prognosis of patients with acute ischemic stroke with large vessel occlusion (AIS-LVO) of anterior circulation after endovascular thrombectomy.Methods The data of anterior circulation AIS-LVO patients treated with endovascular thrombectomy in Neurovascular Center of our hospital from Jan. to Dec. 2019 were retrospectively analyzed. The patients were divided into good collateral circulation (HIR < 0.4) group and poor collateral circulation (HIR ≥ 0.4) group. The clinical data of the 2 groups were compared. According to the modified Rankin scale (mRS) score 90 d after operation, the patients were divided into good prognosis (mRS score ≤ 2) group and poor prognosis (mRS score 3-6) group. The clinical and imaging data of the 2 groups were compared. The influencing factors of the prognosis 90 d after operation were determined by multivariate logistic regression analysis.Results Totally 120 patients were included, including 41 patients in the good collateral circulation group and 79 in the poor collateral circulation group; and 68 in the good prognosis group and 52 in the poor prognosis group. The patients in the poor collateral circulation group were older, and had larger core infarction volume, higher baseline National Institutes of Health stroke scale (NIHSS) score and lower Alberta Stroke Program early computed tomography score (ASPECTS) compared with the patients in the good collateral circulation group, with significant differences (all P < 0.05). The patients in the poor prognosis group were older, with more females, and had higher baseline NIHSS score, larger core infarction volume, lower ASPECTS and successful vascular recanalization rate, and higher incidence of postoperative sICH and HIR compared with the patients in the good prognosis group, with significant differences (all P < 0.05). Multivariate logistic regression analysis showed that age > 80 years (odds ratio[OR]=2.290, 95% confidence interval[CI]1.077-4.869, P=0.031) and HIR ≥ 0.4 (OR=2.974, 95% CI 1.060-8.342, P=0.038) were independent predictors of poor prognosis of patients with anterior circulation AIS-LVO 90 d after endovascular thrombectomy.Conclusion HIR is a reliable measure of collateral circulation before operation. Advanced age and HIR ≥ 0.4 are independent predictors of poor prognosis of patients with anterior circulation AIS-LVO 90 d after endovascular thrombectomy.