Objective To explore the incidence and causes of common adverse events of acute ischemic stroke patients during and after endovascular treatment, and to analyze their effects on prognosis. Methods A total of 513 consecutive patients with acute ischemic stroke, who received endovascular treatment in our hospital from Sep. 2013 to May 2018, were included retrospectively. The patients with 1 or more adverse events (n=230) were included in study group, and those without adverse events (n=283) were included in control group. The incidence and etiology of adverse events were analyzed in both groups. The baseline data, successful recanalization rate, good prognosis rate and mortality in the two groups were compared and analyzed. The relationship between adverse events and clinical prognosis was explored by multivariate logistic regression analysis. Results The total incidence of adverse events was 44.8% (230/513), including intracranial hemorrhage (22.0%, 113 cases), symptomatic intracranial hemorrhage (9.6%, 49 cases), progressive ischemic stroke (23.4%, 120 cases), new territory embolism (6.2%, 32 cases), arterial dissection (1.4%, 7 cases), stent thrombosis (1.9%, 10 cases), reocclusion (4.5%, 23 cases) and so on. Reperfusion injury, futile reperfusion, mechanical injury (caused by stent, catheter or wire) and drugs were responsible for the development of the adverse events. Compared with the control group, the age and the pre-procedural score of National Institutes of Health stroke scale (NIHSS) were significantly higher (t=2.298, P<0.05, and Z=34.378, P<0.01), and the proportion of males and the pre-procedural score of American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology scale (ASITN/SIRs) were significantly lower (χ²=9.614, P<0.01, and Z=13.311, P<0.01) in the study group. Although more passes were significantly performed to achieve successful recanalization in the study group compared with the control group (Z=22.677, P<0.05), the rates of successful recanalization (modified thrombolysis in cerebral infarction graded 2b/3) and good prognosis (modified Rankin scale scored 0-2) 90 d after operation were significantly lower in the study group (χ²=19.903 and 180.191, both P<0.01), but with a significantly higher mortality 90 d after operation (χ²=52.818, P<0.01). The results of the multivariate logistic regression analysis indicated that symptomatic intracranial hemorrhage and progressive ischemic stroke were independent risk factors of poor prognosis of acute ischemic stroke patients after endovascular treatment (both P<0.01). Conclusion Adverse events of acute ischemic stroke patients during and after endovascular treatment can affect the 90-d prognosis. Symptomatic intracranial hemorrhage and progressive ischemic stroke are independent predictors of poor prognosis.