Abstract: Objective To explore the preventive effect of different prostaglandins combined with oxytocin on postpartum hemorrhage after repeated cesarean section in women with scar uterus. Methods A total of 90 pregnant women with scar uterus were randomly divided into group A and group B, with 45 cases in each group. Group A was given vaginal cramping with carboprost methylate suppositories, group B was given carboprost tromethamine injection. Intraoperative blood loss at 2 h and at 2, 24 h after delivery were observed, and the incidence of postpartum hemorrhage, blood transfusion rate and postpartum adverse reactions were compared between the two groups. Results After 2 h postpartum, the activated partial thromboplastin time(APTT), plasma thrombin time(TT)and fibrinogen(Fib)levels in both groups were significantly lower than those before surgery, and the levels of APTT, TT and Fib in group B were significantly lower than those in group A(P<0.05). After drug administration, the duration of uterine contraction in group B was significantly longer than that in group A, and the speed of uterine floor decline was significantly faster than that in group A(P<0.05). The blood loss in group B at 2, 24 h after delivery was significantly less than those in group A(P<0.05). There was no statistically significant difference in the incidence of postpartum adverse reactions between the two groups(P>0.05). Conclusion Carboprost methylate suppositories has similar effect compared with carboprost tromethamine injection in the prevention of postpartum hemorrhage after cesarean section in women with scar uterus. But carboprost tromethamine injection is more effective in promoting uterine contractions, improving blood clotting and reducing postpartum blood loss.