Cervical erosion refers to the ectopic columnar epithelium of the cervix, which is not a true erosion. When the epidermis of the external cervical os is shed and replaced by another epithelial tissue of the cervical os, the new epithelium covering the surface is thin, and even the blood vessels and red tissue below can be seen, which looks like erosion. It is one of the physiological changes of the cervix, not a pathological change. The wrong name "cervical erosion" has been "canceled" in the medical obstetrics and gynecology textbooks in 2008 and replaced by the physiological phenomenon of "ectopic columnar epithelium of the cervix". Physiological ectopic columnar epithelium of the cervix is more common in adolescence, women of childbearing age with strong estrogen secretion, oral contraceptives or pregnancy. Due to the effect of estrogen, the squamous-columnar junction moves outward, and the local cervix changes in appearance like erosion.