A woman with a normal menstrual flow should have an endometrial thickness of between 1.0 and 1.5cm before her period. Menstruation is produced by the stripping of the endometrium, and the endometrium is the target organ of sex hormones, sex hormones in the menstrual cycle is constantly changing, in the menstrual period before the endometrium by estrogen and progesterone stimulation of the thickness of the maximum, about 1.2-1.8cm. after the onset of menstruation of the endometrium necrosis and shedding, the thickness of the thickness gradually decreases, with the end of the end of the menstruation endometrium shedding is complete, the thickness of the endometrium to the end of the cycle to the thinnest stage, between 0.5-0.7cm. At the end of menstruation, the thickness of the endothelium changes to the thinnest stage of the cycle, which is between 0.5 and 0.7 cm. The above values are averages, and the thickness of the endometrium is related to the level of sex hormones in the woman’s body and to the amount of menstruation. If the thickness of the endometrium varies significantly from the normal value, it may indicate the presence of endometrial pathology, and the cause should be clarified and intervention should be carried out in a timely manner.