Endometrial thickening is a common clinical gynecological condition that usually causes bleeding, mostly in the form of irregular vaginal bleeding with increased menstrual flow and prolonged periods. The cause of endometrial thickening is related to excessive secretion of estrogen and lack of progesterone. The endometrium can continuously proliferate under the influence of estrogen leading to thickening, and irregular shedding of the endometrium can occur after estrogen decreases, which can then induce bleeding. The vast majority of endometrial thickening is a reversible lesion or remains a persistent benign state, and only a few cases may develop into malignant lesions after a long period of time without improvement. Endocrine disorders, endometrial polyps, excessive mental stress, and overweight can all trigger endometrial thickening. Endometrial thickening should be diagnosed and treated promptly. Patients with endometrial thickening in adolescence are mostly infertile, basal body temperature should be measured, and ovulation promotion therapy is available for monophasic infertile patients. For endometrial thickening in fertile women, diagnostic scraping is usually sufficient to control bleeding once. If bleeding still occurs after scraping, hysteroscopy or ultrasound should be performed to exclude submucosal myomas, polyps or other organic lesions. In perimenopausal women with thick endometrium, if there are symptoms such as abnormal vaginal bleeding, endometrial scraping or hysteroscopy is recommended, and treatment will be given according to the results of the examination.