Abstract: Successful induction of labor mainly depends on cervical ripening.  Safe and effective cervical ripening intervention can improve the rate of vaginal delivery and reduce complications in patients with unfavorable cervical conditions. In clinical practice cervical ripening should be performed under criteria and guidelines. In addition，maternal individual characters also need be considered to decide the specific plan，which is important to insure health of mothers and infant.At presents，the way of cervical ripening sometimes is selected according to what obstetricians like，for lack of knowledge about mechanisms.  Indications，contraindications and precautions can be better learned by learning about the mechanism of various methods of cervical ripening in order to eradicate adverse outcomes of mothers and infants caused by improper intervention.