The water bladder is one of the common clinical methods to induce labor. The water bladder is usually available for about 6-8 hours and can be dropped out after the opening of the uterus. The water bladder is placed above the inner cervical opening and 200-300ml of saline is injected into the bladder at the same time. After the pregnant woman walks normally, the water bladder gradually dilates the opening of the uterus as well as shortens the cervix by gravity. Under normal circumstances, if the oxytocic bladder promotes the maturation of the cervix and induces contractions, it can be dropped out after the opening of the uterus in about 6-8 hours. If no contractions are induced, the bladder can be removed by the doctor after 12 hours of placement and 80ml-100ml of saline can be injected to avoid intrauterine infection. In addition, aseptic operation needs to be strictly carried out in the process of water sac induced labor, intraoperative and postoperative detection and listening to fetal heartbeat, close observation of maternal body temperature, blood pressure and contractions, and additional antibiotic treatment if necessary to prevent or control infection.