Currently, there are few patients with endometriotic cysts of the ovary (commonly known as chocolate cysts). The etiology is still unclear, and there are various theories of endometrial implantation, lymphatic and venous dissemination, induction, immunomodulation, and so on. The main manifestations are: lower abdominal pain, dysmenorrhea, infertility, abnormal menstruation, etc., and in severe cases, painful intercourse. The diagnosis can be confirmed by ultrasound examination, and blood CA125 can be elevated, but usually does not exceed 200 KIU/L. Treatment objectives: reduction and removal of lesions, pain relief and control, treatment and promotion of fertility, prevention and reduction of recurrence. The surgical options are: fertility preserving surgery (40% chance of recurrence), ovarian function preserving surgery (5% chance of recurrence), and radical surgery (almost no recurrence). Currently, laparoscopy is used as the preferred surgical approach. With the increasing number of clinical cases, an increasing number of cases of coeliac malignancy (>1%) are reported. So, in those cases should one be alert to its malignancy? Some of these rules have been summarized medically: cyst diameter >10 cm or a significant trend of increase, CA125 >200KIU/L, change of pain rhythm, recurrence after menopause, imaging examination suggesting solid or papillary structures within the ovarian cyst or rich blood flow in the lesion. The pathological types are mostly clear cell carcinoma and endometrioid carcinoma. Therefore, it is particularly important to perform rapid intraoperative freezing of the specimen for cases with these high-risk signs. Often the lesion is combined with atypical hyperplasia, which is a precancerous lesion of the former. Treatment is then performed in the same way as ovarian cancer surgery. I hope this article can be helpful to all endometriosis patients! Pay attention to regular review and timely medical consultation for abnormal symptoms.