Differential diagnosis of ovarian teratoma mainly includes ovarian plasma carcinoma, ovarian mucinous cystadenoma, endometriosis, and other tumor-like lesions of ovary. 1. Ovarian plasmacytoid carcinoma: ovarian plasmacytoid carcinoma can be easily confused with ovarian teratoma due to polycystic, polythematous, cystic solid or solid manifestation, which can be differentiated and diagnosed by clinical manifestations, ultrasonography and histologic examination. 2. Ovarian mucinous cystadenoma: mucinous cystadenoma lesions are large, mostly unilateral, multicompartmental, and the wall of the capsule is thicker, and there can be tiny soft papillae inside, which is easy to be confused with ovarian teratoma and need to be identified by pathological and histological examination. 3. Endometriosis: endometriosis is prone to adhesions and chocolate cysts, rectal uterine depression nodules, which are easily confused with immature ovarian teratomas. Since endometriosis has symptoms such as progressive dysmenorrhea and menstrual changes, it can be identified by clinical manifestations and ultrasound. 4. Other tumor-like lesions of the ovary: other physiologic cysts of the ovary (lutein cysts, follicular cysts), tubal cysts, etc. are also easily confused with ovarian teratoma. Ovarian physiologic cysts can usually disappear with the menstrual cycle, and fallopian tube cysts usually have a history of pelvic infectious disease with clearer borders, which can be differentiated by ultrasonography and pathologic histology. Ovarian teratoma in the clinic need to be timely to the hospital for examination and treatment, so as not to delay the condition.