After 20 weeks of gestation or during delivery, the placenta in its normal position is partially or completely detached from the uterine wall before the delivery of the fetus, which is called placental abruption. Placental abruption is a serious complication in late pregnancy, with rapid onset and progression, which can endanger the life of mother and child if not treated in time. The incidence of placental abruption is 4,6‰ to 21‰ in China and 5,1‰ to 23,3‰ in foreign countries. The incidence is related to whether the placenta is carefully examined after delivery. Some mild cases of placental abruption may have no obvious symptoms before delivery, and only during postpartum examination of the placenta, clot pressure is found at the site of abruptio, which is easily ignored in such patients. The abdominal examination shows that the uterus is hard like a plate on palpation and there is pressure pain, especially at the placenta attachment area. The diagnosis of placenta abruptio is hard like a plate: 1. It is not difficult to confirm the diagnosis of placenta abruptio based on history, symptoms, signs and b-type ultrasonography. The symptoms of mild placenta abruptio are mainly distinguished from those of placenta praevia. The signs are not obvious, so careful observation and analysis should be made and the diagnosis should be confirmed with the help of b-mode ultrasound. The symptoms and signs of severe placental abruption are typical and the diagnosis is not difficult. The severity should be judged and laboratory tests should be used to determine whether there is coagulation dysfunction and renal failure. Placenta abruptio attached to the posterior wall of the uterus is not easy to diagnose, and is characterized by unexplained increased uterine tension, not excessive amniotic fluid, and is not in labor, and placenta abruptio should be suspected in those with hyperemesis.