Objective：To summarize the published evidences and to compare effect of prophylactic administration of cefazolin prior to cesarean section and after cord clamping. Methods：Databases of PubMed，Embase，and CENTRAL in the Cochrane Library were searched for randomized controlled trials and effect of prophylactic administration of cefazolin prior to cesarean section and after cord clamping were compared. Results：Six randomized controlled trials with high quality were included in this Meta analysis. Preoperative administration significantly reduced the risk of postpartum endometritis（RR=0.57，95%CI=0.36 to 0.90，P=0.02）. Preoperative admin－istration of cefazolin was not associated with significant reduction in the risk of wound infection（RR=0.70，95%CI=0.43 to 1.12） and urinary tract infection（RR=1.19，95%CI=0.53 to 2.63）. Furthermore，preoperative administration of cefazolin did not significantly af－fect proven neonatal sepsis（RR=0.82，95%CI=0.47 to 1.42），suspected neonatal sepsis cases which require workup（RR=0.94，95%CI=0.72 to 1.22） and neonatal intensive care unit admissions（RR=0.90，95%CI=0.62 to 1.28）. Conclusion：Prophylactic administra－tion of cefazolin prior to cesarean section can significantly decrease the incidence of postpartum endometritis.