Objective: To investigate the clinical effects of applying the magnetic resonance double mismatch technique to endovascular treatment of acute anterior circulation, large vessel occlusion with cerebral infarction in an unknown time window. Methods: The research work was carried out in our hospital, the work was carried out from November 2018 to November 2019, the patients with acute anterior circulation large vessel occlusion with cerebral infarction who were treated in our hospital during this period, 100 patients, 50 patients with an unknown time window and 50 patients with definite time window were selected, and they were named as the experimental and control groups, given different examination methods, were given to investigate the clinical treatment effect. Results: Patients' data on HIHSS score before treatment, the incidence of intracranial hemorrhage and rate of Mrs?2 rating after 90 days of treatment were not significantly different(P>0.05), which was not meaningful. The differences in data between the two groups concerning HIHSS scores were relatively significant before, and after treatment(P<0.05). Conclusion: The magnetic resonance double mismatch technique will be applied in the endovascular treatment of acute anterior circulation large vessel occlusion with cerebral infarction of unknown time window.