Objective:To investigate the efficacy and safety of precise mechanical thrombectomy based on ABC 2D scale in acute intracranial large artery occlusion stroke (ALVOs). Methods:A prospective study was performed. Two hundred and two patients with ALVOs accepted early mechanical thrombectomy in Department of Neurology, Maoming Clinical School of Guangdong Medical University from January 2021 to February 2022 were enrolled. They were randomly divided into experimental group ( n=102) and control group ( n=100). Stent retriever partially retracted with intermediate catheter for mechanical thrombectomy (SWIM) was the first choice for patients in control group. ABC 2D scale was used to prejudge the pathogenesis of patients in experimental group: patients with scores of 0-3 were considered as having embolic occlusion and a direct aspiration first pass technique (ADAPT) was the first choice, and SWIM would be chosen if suction catheter could not be in place; patients with scores of 4-7 were considered as having intracranial atherosclerotic stenosis occlusion and SWIM was the first choice. The clinical data, surgical effectiveness, surgical safety, and good prognosis rate 90 d after mechanical thrombectomy (modified Rankin scale scores of 0-2 as good prognosis) of the 2 groups were compared. Results:Experimental group had significantly shorter time from puncture to recanalization (51.0[35.0, 78.5] min vs. 67.0[45.0, 100.0] min), and statistically lower NIHSS scores 24 h after mechanical thrombectomy (10.00[4.75, 16.25] vs. 13.00[8.00, 19.00]), significantly higher good prognosis rate 90 d after mechanical thrombectomy (69.6% vs. 46.0%), statistically lower mortality 90 d after mechanical thrombectomy (3.9% vs. 13.0%) compared with control group ( P<0.05). No significant differences were noted in first-pass effect rate, successful vascular revascularization rate, or incidences of symptomatic intracranial hemorrhage (sICH) and ectopic embolization between the control group and experimental group ( P>0.05). Conclusion:Patients with ALVOs accepted early mechanical thrombectomy can have shorter time from puncture to vascular recanalization and better prognosis after etiologically prejudging by ABC 2D scale for thrombectomy.