Abstract: Objective: To investigate the clinical symptoms and MRI features of ovarian malignant germ cell tumors. Methods: Clinical data and MRI images of seven cases with ovarian malignant germ cell tumors confirmed by operation and pathology were retrospectively analyzed, including 1 case of dysgerminoma, 3 cases of yolk sac tumor, 2 cases of immature teratoma and 1 case of mixed germ cell tumor. Results: The clinical symptoms of 7 patients were 1 case of abdominal pain, 3 cases of abdominal mass and 3 cases of abdominal distension. Tumor markers levels: AFP was significantly increased in 6 cases; CA125 was elevated in 3 cases. MRI features: All the tumors were unilateral lesions, including 4 on the right side and 3 on the left side. There were 6 cases of quasi-circular shape and 1 case of lobular shape, the boundary is clear. The maximum diameter of all lesions is greater than 9cm. One case of dysgerminoma was mainly composed of solid components, while the other 6 cases were cystic. 1 case of dysgerminoma saw low signal separation, 2 cases of immature teratoma saw small cystic fluid signal area, and scattered fat signal. Enhanced scanning: 1 case of dysgerminoma was moderately enhanced, with continuous enhancement separation. In 6 cases, the solid part of cystic neoplasm was continuously strengthened, 3 cases of yolk sac tumor showed "honeycomb sign", and 2 cases of immature teratoma showed multiple cystic unenhanced areas. There were 5 cases with peritoneal effusion and 2 cases with yolk sac tumor with irregular thickening of the omentum. In one case, dysgerminoma was accompanied by pelvic and retroperitoneal lymph node enlargement, but no lymph node enlargement was observed in other cases. Conclusions: Combined with clinical manifestations, preoperative tumor marker detection and MRI features, it is helpful for the correct diagnosis and differential diagnosis of ovarian malignant germ cell tumors.