Objective: The aim of this study was to evaluate thrombi composition and its association with clinical, laboratory, and neurointerventional findings in patients with acute ischemic stoke (AIS) treated by mechanical thrombectomy (MT) . Methods: Seventy patients were treated by mechanical thrombectomy using a stent retriever and/or aspiration catheter between August 2018 and December 2019 at the Second Affiliated Hospital of Nanjing Medical University. The retrieved thrombi were quantitatively analyzed to quantify red blood cells, white blood cells, and fibrin by area. We divided the patients into two groups, a fibrin-rich group and an erythrocyte-rich group which were based on the predominant composition in the thrombi. The groups were compared for clinical, and neuro-interventional data. Results: The retrieved thrombi from 49 patients with acute stroke from internal carotid artery, middle cerebral artery, or basilar artery occlusion were histologically analyzed byhematoxylin-eosin (HE). Erythrocyte-rich thrombi were present in 30 cases, while fibrin-rich thrombi were present in 19 cases. A cardioembolic etiology was not significantly more prevalent among the patients with fibrin-rich thrombi than among those with erythrocyte-rich thrombi. All other clinical and laboratory characteristics remained the same. Patients with fibrin-rich thrombi had a shorter time interval between arrival and recanalization (68.4229.99 vs 87.0737.29，P=0.04), and shorter procedure times (1.63 vs 2.20, P=0.04). The proportion of stent retriever combined aspiration?as first-line thrombectomy strategy in fibrin-rich thrombi group was higher than in erythrocyte-rich group (84.21% vs 56.67%, P=0.03). Conclusions: Fibrin-rich thrombi may influence the thrombectomy strategy and be associated with stent retriever combined aspiration thrombectomy strategy, reduced recanalizational time and procedure times. Larger confirmatory prospective studies are warranted.