Thickness of endometrium is related to follicle stimulating hormone, in addition to endometrial hyperplasia, endometrial cancer and other diseases. 1. Follicle stimulating hormone: when the follicle stimulating hormone in the body increases and the follicle is under normal development, the thickness of the endometrium will also change under the effect of estrogen, but generally will not exceed the normal range. 2. Endometrial hyperplasia: it is a pathological reaction formed when the endometrium is stimulated by estrogen for a long time. If the secretion of estrogen is not regulated in time, it is easy to cause abnormal endometrial hyperplasia and abnormal uterine bleeding, and it may develop into malignant endometrial lesion in a long time. 3. Endometrial cancer: malignant tumor of endometrium may be manifested as endometrial thickening and vacuolation. Once endometrial thickening is found, pathologic examination and vaginal ultrasonography should be completed as soon as possible, and then targeted treatment should be carried out according to the diagnostic results.