Endometriosis is a benign disorder,but it shows some characteristics of malignancy and has a tendency toward malignant transformation. The risk of endometriosis malignant is between 0.7% and 1.0%,in which endometriosis of the ovary is predominant. It is recently reported that the tendency of malignant transformation of endometriosis can be related to hormone,disease progress,age and menstrual and obstetrical history. The current treatment of endometriosis malignancy mainly focuses on surgery,and is aided with comprehensive treatments by chemotherapy,radiation treatment and hormone therapy. To the patient who has the tendency of endometriosis malignancy,exploratory laparotomy should be operated to achieve early diagnosis and treatment.