Objective To investigate the predictive factors of symptomatic intracranial hemorrhage(SICH) and the effect on outcomes after mechanical thrombectomy in patients with acute ischemic strokecaused by anterior circulation tandem occlusion. Methods From January 2014 to September 2018, patients with acute ischemic stroke caused by anterior circulation tandem occlusion and treated by endovascular mechanical thrombectomy from the Departments of Neurology in 5 general hospitals (the First Affiliated Hospital of Henan University of Science and Technology, the Affiliated Hospital of Yangzhou University,General Hospital of Eastern Theatre Command of PLA, Yijishan Hospital of Wannan Medical College,Xinqiao Hospital of Army Medical University of PLA) were enrolled retrospectively. SICH was evaluated according to the criteria of Heidelberg Bleeding Classification. The functional outcome was assessed by the modified Rankin Scale score at 90 d after onset, and 0-2 was defined as good outcome. Multivariate logistic regression analysis was used to determine the effect of SICH on the outcome at 90 d and the independent risk factors for SICH. Results A total of 124 patients with acute ischemic stroke caused by anterior circulation tandem occlusion and treated by endovascular mechanical thrombectomy were enrolled in this study. Among them, 19 (15. 3％) had SICH, 60 (48. 4％) had good outcomes, and 28 (22. 6％) died. The incidence of poor outcomes (94. 7％ vs. 43. 8％; χ2 = 16. 708, P < 0. 001 ) and mortality (57. 9％ vs.16. 2％; P < 0. 001 ) in the SICH group were significantly higher than those in the non-SICH group.Multivariate logistic regression analysis showed that SICH was an independent risk factor for poor outcome(odds ratio [OR] 27. 78, 95％ confidence interval [CI] 2. 60-96. 70; P = 0. 006), while larger infarct core(low ASPECT score) was the only independent predictor of SICH (OR 2. 63, 95％ CI 1. 18-5. 88; P =0. 018). Conclusion In patients with acute ischemic stroke caused by anterior circulation tandem occlusion and treated by endovascular mechanical thrombectomy, SICH is associated with poor outcome and higher mortality at 3 months, and larger preoperative infarction core is an independent predictor of SICH.