Generally speaking, the thickness of endometrium is less than 10mm. From puberty to premenopause, the thickness of endometrium is changing with menstrual cycle, which is a continuous change process. Taking the normal menstrual cycle of 28 days as an example, the thickness of endometrium in the proliferative phase is growing from 0.5mm to 5mm, the thickness of endometrium in the secretory phase should reach 10mm, the endometrium is shed in the menstrual phase, and then a new menstrual cycle starts again. After menopause the endometrium should show atrophic changes. Endometrial thickening is mostly associated with excessive estrogen stimulation of endometrial growth, which is mostly seen in postmenopausal patients who are undergoing single estrogen replacement therapy, long-term use of health care products containing large amounts of estrogen, anovulatory uterine bleeding, polycystic ovary syndrome, obesity, hypertension, diabetes mellitus, late menopause, and functional tumors of the ovaries that secrete estrogen. Patients. For patients with persistent endometrial thickening, especially for menopausal women with endometrial thickness greater than 4-5 mm, diagnostic scraping should be performed in a timely manner and the scraped endometrium should be sent to pathology department for clear diagnosis. Most of the endometrial thickening is due to excessive estrogen stimulation without progesterone antagonism.