The specific procedure of amniocentesis includes; preoperative examination, sterilization, ultrasound localization, puncture, and compression of the puncture site. 1. Preoperative examination: first of all, before amniocentesis, ultrasound as well as blood test are needed, mainly to exclude contraindications to amniocentesis. Don’t eat too much on the day of the puncture. 2. Sterilization: the bulging part of the uterus is sterilized with iodine-vapor. 3. Ultrasound localization: ultrasound localization is performed to choose a suitable puncture point. 4. Puncture: The puncture needle is passed through the abdominal wall, uterine wall, and within the amniotic membrane in turn, and an appropriate amount of amniotic fluid is extracted. 5. Compression of the puncture point: the puncture point is then compressed with gauze and observed for one to two hours. If there is no discomfort, the puncture is successfully completed. Amniocentesis is a prenatal diagnostic technique that needs to be performed in strict accordance with medical advice.