Introduction: The aim of this study was to discuss the safety of rapid administration of 4°C hypothermic normal saline into the occluded vessels using an intra-arterial catheter to induce mild hypothermia following endovascular thrombectomy in patients with acute large vessel occlusion cerebral infarction. Methods: We selected 78 patients with acute large vessel occlusion cerebral infarction who underwent endovascular thrombectomy in the Department of Neurology of our hospital from January 2020 to July 2022 and achieved TICI 2b recanalization. Result: Twenty-five patients were administered 500 mL of 4°C hypothermic normal saline in the occluded vessels at a rate of 25 mL/min to induce mild hypothermia. Twenty pairs of subjects conformed to strict matching and were finally included in the statistical analysis. The two groups of patients differed significantly in white blood cell count and percentage of neutrophils (p < 0.05); however, there were no significant differences in D-dimer, procalcitonin, and BNP levels. The two groups of patients did not differ significantly with respect to the incidence of the following indicators: upper gastrointestinal bleeding; pulmonary infection; venous thrombosis; vasospasms; seizures; and chills (p > 0.05). Conclusion: Mild therapeutic hypothermia in target vessels plus endovascular thrombectomy was shown to be safe in patients with acute large vessel occlusion cerebral infarction.