Currently, early reperfusion is considered as the most effective therapy for the treatment of acute ischemic stroke (AIS). Over the past 20 years, intravenous tissue plasminogen activator (IV tPA) has been demonstrated to be the only effective therapy for AIS. More recently, several large randomized clinical trials have concluded the superiority of endovascular mechanical thrombectomy for AIS. Furthermore, with the development of materials and techniques, the occluded artery can be recanalized with high percentage (60%-90%), and the rate of recanalization is still being improved. A great number of AIS patients are now eligible for revascularization therapy and there should be a good prognosis of AIS after recanalizing the occluded artery using mechanical thrombectomy. However, things are never as simple as wished to be. The rate of patients with functional independence is less than 50% and over 15% patients died at 3 months post thrombectomy. The discrepancy between the functional outcome and recanalization rates encourage researchers to explore strategies that further improving the functional outcome of AIS patients.