Objectives: To improve the knowledge about retroperitoneal teratoma and reduce the misdiagnosis rate by reviewing a case of retroperitoneal teratoma that was misdiagnosed as an ovarian tumor and analyzing the reasons for misdiagnosis. Case Report: The medical records of a patient with retroperitoneal teratoma misdiagnosed as an ovarian tumor were retrospectively analyzed. The retroperitoneal teratoma misdiagnosed as an ovarian tumor was completely removed through laparoscopy, and the postoperative pathological examination indicated it was a retroperitoneal mature cystic teratoma. Conclusion: Thorough auxiliary examinations should be performed for pelvic space occupying diseases, in addition to the conventional gynecological examination and rectal examination, and CT and MRI should be performed for determination of mass localization. Laparoscopic exploration as an optional surgery could be considered by skilled gynecologists.