Ovarian teratoma is the most common germ cell tumor, the cause of which is unknown and may be due to genetic factors, living habits, and environmental factors. 1. Genetic factors: current research shows that some patients with ovarian teratoma have family history of the tumor, therefore, ovarian teratoma may be caused by heredity. 2. Lifestyle habits: if the patients are in the situation of high pressure, tension and bad rest for a long time, it may make the immunity of the body decrease, which may induce the abnormal proliferation of female ovarian tissues, and then form ovarian teratoma. 3. Environmental factors: In addition, if the patient is in the environment of serious air pollution and radiation for a long time, it may also induce the formation of ovarian teratoma. To sum up, the causes of ovarian teratoma are relatively many, and it is suggested that patients should go to the hospital in time to consult the doctor, clarify the cause of the disease and treat it.