Complex endometrial hyperplasia is classified as endometrial hyperplasia not associated with atypical hyperplasia and is not a precancerous condition. In 2003, the World Health Organization classified endometrial hyperplasia according to the degree of endometrial hyperplasia into hyperplastic endometrium, simple hyperplasia, complex hyperplasia and atypical hyperplasia, which was revised in 2014 and classified into endometrial hyperplasia not accompanied by atypical hyperplasia (EH) and endometrial hyperplasia not accompanied by atypical hyperplasia (AH), among which complex hyperplasia belongs to EH, which is not pre-cancerous, while AH belongs to precancerous lesions. Endometrial hyperplasia is the result of long-term single estrogen stimulation, and its high-risk factors include polycystic ovary syndrome, abnormal uterine bleeding with ovulation disorders, and obesity, etc. It is recommended that women with irregular menstruation, especially with prolonged menstrual cycles, should be treated in a timely manner in order to avoid the development of pre-cancerous lesions and cancer.