Abstract: Objective To investigate the risk factors for increased red blood cells (RBCs) transfusion ratio in the women with postpartum hemorrhage (PPH). MethodsThis case-control study obtained the inpatient medical records of 112 441 pregnant women from 37 hospitals in 2011. There were 4 131 women diagnosed with PPH, record data of those patients were analyzed, including basic characteristics of patients, the level of hospital, pregnancy related complications, prenatal hemoglobin (Hb), mode of delivery, details of postpartum blood loss and blood transfusion, and maternal and neonatal outcomes. Multiple logistic regression analysis was used to identify risk factors for increased RBCs transfusion ratio. ResultsThere were 61 339（54.6%）out of 112 441 women received with Cesarean section and 637 (15.4%) out of 4 131 women with PPH had blood transfusion, one to four units of RBCs were sufficient for a majority of those patients. It demonstrated that level of hospital, multiple, placenta preiva, abruptio placenta, pre-eclampsia or eclampsia, pre-delivery hemoglobin, gestational age and labor method were independent risk factors for RBCs transfusion. Conclusion Cesarean section and pregnant complications are important risk factors for blood transfusion in women with PPH .