To evaluate the therapeutic role of lymphadenectomy on patients with malignant ovarian germ cell tumor (MOGCT) and to investigate the risk factors of lymph node metastasis. Patients of MOGCT between 1988 and 2013 with definite lymph node information were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. Survival curves were estimated using the Kaplan-Meier method, and Cox regression analyses were performed to evaluate the effects of clinical and pathologic variables on survival. 2424 MOGCT patients with information on lymph nodes were included. Of the entire cohort, 46.2% patients received lymphadenectomy. The most common (42.2%) histologic type was teratoma, and 70.6% patients had FIGO stage I disease. Cox proportional model verified that age, grade, and log odds of positive lymph nodes (LODDS) were independent prognostic factors. Subgroup analysis showed that the association between the lymph node resection and better survival in the different age cohort. Lymphadenectomy is not recommended for children (0-14years). For patients 40years of age and older, and for those who have the dysgerminoma type or endodermal sinus type, lymphadenectomy had an outstanding therapeutic role. As a parameter to assess lymph node status, LODDS could be used to classify MOGCTs.