Endometriosis has the potential to become cancerous. Endometriosis, clinically known as endometriosis, is caused by the presence of endometrial tissue outside the body of the uterus for various reasons. The ectopic endometrium can invade any part of the body, the most common site being the ovaries. Endometriosis is one of the most common diseases in women of reproductive age. Although it is histologically benign, it has malignant behaviors such as proliferation, infiltration, metastasis and recurrence, and a certain percentage of them will become malignant. However, its malignant rate is very low, about 0.7%-1%, of which 80% occur in the ovaries, leading to ovarian cancer. Patients with the following high-risk factors are prone to cancer, such as obesity and long-term application of estrogen; long duration of disease is also one of the high-risk factors for malignant transformation of endometriosis, and the longer the duration of disease, the higher the incidence of malignant transformation; early menarche, short menstrual cycle, and increased ovulation at menopause party can increase the probability of malignant transformation of damaged epithelium, which can increase the incidence of endometriosis and thus increase the rate of malignant transformation; environmental factors such as long-term exposure to dioxin, which can stimulate carcinogenic substances, can increase the incidence of malignant transformation. Environmental factors such as long-term exposure to dioxins, which can stimulate carcinogenic substances, are mainly derived from incineration, the use of renewable resources and the production of chemicals such as herbicides and preservatives; Danazol, one of the drugs used to treat endometriosis, is an androgen analogue, and one of the side effects of long-term use of Danazol is the development of hyperandrogenic symptoms, while androgen excess has a close relationship with the occurrence and development of ovarian cancer. As mentioned above, endometriosis can become cancerous and is one of the high-risk factors for ovarian cancer. However, the probability of cancer is very low, so patients should actively treat and regularly review the disease after diagnosis and try to avoid the above-mentioned high-risk factors that cause ovarian cancer.