Objective: To investigate the predictive value D-dimer for postpartum hemorrhage in patients with scarred uterus and risk factors of postpartum hemorrhage in patients with scarred uterus. Methods: A total of 285 pregnant women with scarred uterus who were treated in Jiangyin Affiliated Hospital of Nanjing University of Traditional Chinese Medicine from May 2020 to May 2022 were selected, 50 women with postpartum hemorrhage were included in a postpartum hemorrhage group, and 235 women without postpartum hemorrhage were included in a non-postpartum hemorrhage group. The clinical data and prenatal serum D-dimer levels were compared between the 2 groups, and the predictive value of D-dimer levels for postpartum hemorrhage in patients with scarred uterus was analyzed. Results: The prenatal serum D-dimer level in the postpartum hemorrhage group was higher than that in the non-postpartum hemorrhage group (P<0.05). The receiver operating characteristic (ROC) curve analysis showed that the prenatal serum D-dimer level predicted the area under the curve (AUC) of postpartum hemorrhage in patients with scarred uterus was 0.849, 95%CI was 0.802 to 0.907 (P<0.05), sensitivity was 0.791, and specificity was 0.972. The single factor analysis showed that age, pregnancy times, gestational weeks, curettage times, prolonged labor process, uterine fundus height at delivery, neonatal birth weight, pregnancy complications, uterine incision tear, and uterine atony in the postpartum hemorrhage group were significantly different from those in the non-postpartum hemorrhage group (all P<0.05). The multivariate logistic regression analysis showed that age, pregnancy times, gestational weeks, the times of curettage, fundus height at delivery, birth weight of newborns, pregnancy complications, and uterine incision tear were the risk factors for postpartum hemorrhage in patients with scarred uterus (all P<0.05). Conclusion: Age, pregnancy times, gestational weeks, times of curettage, fundal height at delivery, birth weight of newborns, pregnancy complications, and uterine incision tear are risk factors for postpartum hemorrhage in patients with scarred uterus. Prenatal serum D-dimer level can predict the occurrence of postpartum hemorrhage in patients with scarred uterus in advance, and targeted measures can be taken in time to improve the prognosis in clinic.