Because there are many elastic fiber nets on the vaginal wall, it can keep the vagina elastic and tight. Therefore, if the elastic net of vagina is broken, it will lead to vaginal relaxation. Common factors include frequent or intense sexual life, abortion, drug abortion, childbirth and so on. It may lead to rupture of vaginal elastic net and vaginal relaxation. And with the increase of women's age, the decrease of estrogen level leads to muscle.