To evaluate the effectiveness and safety of anticoagulants in ischaemic stroke primary or secondary prevention and treatment, we searched The Cochrane Library and MEDLINE to find high quality evidence and summarized the available evidence. The results showed that routine immediate anticoagulant therapy in patients with acute ischaemic stroke should not be recommended because it increased the risk of hemorrhage with ineffective reduction to the risk of death or disability. For the high risk group with cardiogenic embolism, anticoagulant therapy could safely and effectively reduce the incidence of stroke or other vascular events. However, for non-cardiogenic embolism group, anticoagulant therapy was hard to balance the benefits and harms.