Abstract： Objective To evaluate the value of MR angiography in thrombolytic therapy of acute ischemic stroke. Methods According to inclusion criteria, 65 patients who also having large vessel occlusion were selected, and they were performed rt-PA treatment (38 patients) and routine treatment (27 patients) within 3-6 hours of onset of symptoms, respectively. Mann-Whitney U test and chi square test were performed to compare the clinical and MR imaging baseline index and the clinical outcome between the two groups respectively. Clinical outcome was assessed after 3 months using a dichotomized modified Rankin scale score.Data were also compared with the combined analysis of the ATLANTIS, ECASS, NINDS rt-PA trials. Resets The difference of clinical outcome in 3 months between the two groups was significant (P < 0. 05) and the median of the two group was 1 and 3, respectively. The ratio of favorable outcome (mRS 0-1) in the two groups was 52. 6% (20/38) and 33.3% (9/27), respectively. Conclusion MR angiography plays an important role in thrombolytic therapy of acute ischemic stroke and it should be used to consummate the conventional inclusion criteria, the patients with large vessel occlusion should be treated by rt-PA.