Objective To explore the value of magnetic resonance imaging (MRI) combined with positron emission tomography (PET-CT) in the preoperative diagnosis of brain glioma. Methods A total of 84 cases of patients with high suspicion of brain glioma admitted to neurosurgery department of our hospital in the past two years (from March 2016 to March 2018) were given MRI and PET-CT before operation. The results of postoperative pathological examination were taken as reference to evaluate the value of separate MRI and MRI combined with PET-CT in the preoperative diagnosis of brain glioma. Results Postoperative pathology of 84 cases of patients confirmed 21 cases of highgrade glioma, 55 cases of low-grade glioma and 8 cases of negative glioma, and all were single tumors. The sensitivity, specificity and accuracy of MRI for preoperative diagnosis of brain glioma were 96.05% (73/76), 100% (8/8) and 96.43% (81/84) respectively, and the accuracy of glioma grading was 75.00% (57/76). The sensitivity, specificity and accuracy of MRI combined with PET-CT for preoperative diagnosis of brain glioma were 98.69% (75/76), 100% and 98.81% (83/84) respectively, and the accuracy of glioma grading was 93.42% (71/76). The accuracy of MRI combined with PET-CT was significantly better than that of MRI in the preoperative evaluation of glioma (P<0.05). Conclusion MRI combined with PET-CT has high sensitivity, specificity and accuracy in the preoperative diagnosis of glioma, and it can more accurately assess the degree of tumor malignancy, provide more comprehensive and accurate information of glioma, and help to formulate more scientific and reasonable treatment regimen in clinical practice, and it has a high clinical diagnostic value.