An enlarged uterus is indicated on ultrasound by measuring the three diameters of the uterus on ultrasound, which exceed the normal uterine dimensions in length, width and thickness. A normal uterus is 7-8cm long, 4-5cm wide and 2-3cm thick, if it exceeds the range, it indicates an enlarged uterus. The causes of uterine enlargement are manifold: I. The proliferation of elastic fiber tissue in the myometrium of polygamous women between smooth muscles and around blood vessels can lead to uterine enlargement. Second, primary uterine vascular lesions can lead to uterine hypertrophy. Third, the continuous stimulation of estrogen can make the myometrium hypertrophy. Clinically, we can often see patients with functional uterine bleeding, especially the longer course of the disease have different degrees of uterine enlargement. Fourth, chronic adnexitis, pelvic connective tissue inflammation and chronic myositis of the uterus can cause myometrial collagen fiber proliferation, so that the uterus fibrosis, uterine enlargement. Fifth, pelvic stasis can cause uterine connective tissue hyperplasia, can also lead to uterine enlargement. Sixth, the case of uterine adenomyosis, uterine fibroadenoma, can cause the uterus progressive enlargement. In the case of uterine fibroids, uterine enlargement can occur. Eight, malignant lesions of the endometrium can also cause enlargement of the uterus.