The severity of teratoma is directly related to the nature of the tumor. There are usually two types, one is mature teratoma and the other is immature teratoma. Due to its hereditary nature, it can occur at any age, but 20-40 years is a high incidence group. Mature teratoma is a benign tumor and immature teratoma is a malignant tumor that occurs in young people, usually unilateral, large, solid tumors with a high rate of recurrence and metastasis. For teratoma, early surgery is recommended to determine whether the teratoma is benign or malignant by the pathological results after surgery. Regular follow-up after surgical excision of benign tumors is sufficient for no further recurrence. If the teratoma belongs to immature type, that is, malignant tumor, the surgical resection is more extensive, and radiotherapy and other treatments have to be done after surgery, which is more serious in this case. Therefore, once a teratoma is diagnosed clearly, regardless of its size, early surgical removal is recommended.