Objective: To evaluate the effectiveness and safety of mechanical thrombectomy treatment in patients with acute ischemic stroke (AIS),and to explore influential factors of the clinical prognosis preliminarily.Methods: Clinical data of 26 patients with acute cerebral arterial occlusion treated with mechanical thrombectomy in Peking University Third Hospital from January 2014 to June 2017 were retrospectively collected. The immediate effects of the 26 patients in this group after mechanical thrombectomy treatment were analyzed,The national institutes of health stroke scale (NIHSS) scores between preoperative and at discharge of the 26 patients in this group were compared,and modified Rankin scale (mRS) scores of 90 days post operation were analyzed to assess the prognosis of the 26 patients in this group.Results: (1)In this group, 23 patients (88.5%) achieved vascular recanalization evaluated by thrombolysis in cerebral ischemia scale scores [thrombolysis in cerebral ischemia scale (TICI) scores,3/2b grades were recognized as vascular recanalization],19 patients of them reached TICI grade 3 and 4 atients reached TICI grade 2b. In this group 3 patients (11.5%)encountered symptomatic intracranial hemorrhage,2 patients of them recovered after cerebral hemorrhage absorbed and 1 patient died of massive cerebral hemorrhage. In this group 4 patients (15.4%) died after mechanical thrombectomy treatment,2 patients died of hernia of the brain caused by severe cerebral edema,1 patient died of symptomatic intracranial hemorrhage and 1 patient died of extensive subarachnoid hemorrhage.(2)The assessment of NIHSS scores at discharge(5.3±2.1)showed significantly lower than those preoperatively(12.6±4.2), P<0.01,and in this group 12 patients (46.2%) achieved favourable prognosis ( defined as mRS scores 0-2),6 patients of them reached mRS 0 score,4 patients reached mRS 1 score and 2 patients reached mRS 2 scores.Conclusion: Mechanical thrombectomy with stent retriever contributed to a high rate of vascular recanalization and favourable prognosis,but some patients had poor prognosis,suggesting that we should screen the enrolled patients strictly.