Objective: To investigate the efficacy and safety of endovascular treatment in patients having acute ischemic stroke with over-time window under DWI-FLAIR mismatch. Methods: From January 2018 to January 2020, 80 patients who met the research criteria in the First Central Hospital of Baoding, China were selected. According to the time of onset, they were divided into test group and control group, with 40 cases in each group. Forty patients in the test group were beyond time window (6~24h) and the MRI showed a DWI-FLAIR mismatch. Forty patients in the control group were within the time window (< 6h). All patients received endovascular treatment (EVT). The mRS, NIHSS and infarct volume of patients in the test group were compared and analyzed before and 30 and 90 days after treatment, as well as the indicators of both groups of patients before and after treatment, to determine therapeutic effect in patients receiving EVT beyond time window. Meanwhile, the recanalization of the blood vessel and the incidence of cerebral hemorrhage of patients in both groups were compared to determine the safety in patients receiving EVT beyond time window under DWI-FLAIR mismatch. Results: The mRS, NIHSS and infarct size in the test group were significantly improved before and 30 and 90 days after treatment (p<0.05). The test group showed no significant difference in mRS, NIHSS and other indicators when compared with the control group (p>0.05). There was no significant difference in the rate of recanalization of the blood vessel and intracranial hemorrhage after treatment between both groups (p>0.05). Conclusion: DWI-FLAIR mismatch can be used as an objective imaging basis for intravascular interventional therapy in patients with stroke with over-time window and large vessel occlusion. It has the advantages of short examination time, non-invasiveness, no need for contrast agents, simple implementation, clear guidance. doi: https://doi.org/10.12669/pjms.37.2.3293 How to cite this:Cao S, Dong H. Predictive value of DWI-FLAIR Mismatch in patients with Ischemic Stroke and receiving Endovascular treatment beyond Time Window. Pak J Med Sci. 2021;37(2):466-471. doi: https://doi.org/10.12669/pjms.37.2.3293 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.