Thickness of the uterine lining is normal if it is physiologic. Because women’s endometrium sheds with the menstrual cycle, the endometrium is in a state of thickening before menstruation, and after menstruation is clean, the endometrium is relatively thin. If the endometrium is thicker and has uneven echogenicity after menstruation, there may be endometrial lesions, and hysteroscopy or endometrial biopsy should be performed to remove the endometrial tissues and send them to the pathologist for clarification of the nature of the endometrial lesions. If the endometrium is complicated hyperplasia or atypical hyperplasia, it is relatively serious, and if left untreated, cancer of the endometrium may occur. If the endometrium is simple hyperplasia or normal stage endometrium, it is normal and can be observed. Therefore, thick endometrium should be examined in time to determine whether it is serious or not.