Acute ischemic stroke (AIS) has the characteristics of high morbidity, disability and mortality. Intravenous thrombolysis with recombinant tissue plasminogen activator (rt-PA) for AIS in time window is an effective treatment recommended by domestic and overseas guidelines. However, intravenous thrombolysis has shortcomings, such as short time window, low recanalization rate and high risk of bleeding. Therefore, in recent years, studies on prolonging the time window, using low-dose rt-PA or a new generation of thrombolytic agent, and thrombolysis combined with anti-thrombotic therapy have been carried out worldwide. Based on the studies on intravenous thrombolysis, this paper discusses several issues, including extending time window, low-dose rt-PA thrombolysis, and new generation of thrombolytic agent.