Carbetocin is a synthetic long-acting oxytocin 8-peptide analogue with agonist properties. Its clinical and pharmacological properties are similar to those of naturally produced oxytocin. Like oxytocin, cabetoxin binds to the oxytocin receptor of uterine smooth muscle and causes the rhythmic contraction of the uterus. On the basis of the contraction of the original chemical book, it increases its frequency and uterine tension. In the non pregnant state, the content of oxytocin receptor in uterus is very low, which increases during pregnancy and reaches the peak at delivery. Therefore, cabetoxin has no effect on non pregnant uterus, but has an effective uterine contraction effect on pregnant uterus and newly delivered uterus.