Ovarian teratoma is a common gynecologic tumor that can occur at any age. However, 80-90% are of reproductive age, of which more than 97% are benign and 1-3% are malignant. Ovaries are the most frequent site of teratoma, posterior peritoneum, mediastinum, head and neck, male testes, and fetal sacro-caudal can occur. In fact, teratoma is a bad embryo, most of it comes from an empty egg fertilized by a haploid sperm, or a fetus within a fetus, and it contains tissues from different germ layers, commonly skin, hair, oil, but also teeth, scalp, thyroid, nerve tissue, and teratoma (also considered as an embryo). They are present before birth and are usually detected in adulthood. It is usually asymptomatic. Most of them are detected by ultrasound or gynecological examination, and the main clinical treatment is laparoscopic surgery. Whether it is benign or malignant is determined by pathological examination after surgery. Regular post-operative review is needed. Because individual teratoma may recur, the recurrence can be ipsilateral or contralateral.