Abstract: 　Objective　To investigate the effects of residual amniotic fluid index (AFI) on pregnancy and newborn outcome in preterm premature rupture of the membranes (PPROM). Methods The clinical data of 653 cases of pregnant women with PPROM admitted to hospital from February 2005 to December 2012 were retrospectively analyzed. All participants were divided into two groups according to AFI cutoff value determined by ROC curve, group A (AFI ≤ 40 mm, n=252) and group B (AFI > 40 mm, n=401). Pregnancy outcome and newborn prognosis of the two groups were compared and analyzed. Results The interval between rupture of membranes and delivery in group A was (69.54±14.25) h, significantly shorter than that in group B (136.96±9.54) h (P<0.01). There was no difference in gestational age at membrane rupture, cesarean section rate, the rates of fever and placental abruption between two groups (P>0.05). The case fatality rate of newborns in group A was 3.57%, significantly higher than that of group B (1.25%) (P<0.05). However, there was no difference in 1-minute Apgar score, birth weight, sex ratio, gestational age, the rates of asphyxia, fetal distress and perinatal infection between two groups (P>0.05). Logistic regression analysis revealed that AFI≤40mm was an independent risk factor for neonatal death (OR=2.31, P<0.05) and asphyxia (OR=3.05, P<0.05), moreover, gestation age at membrane rupture was an independent risk factor for neonatal death (OR=1.79, P<0.05). Conclusions AFI was related closely with several adverse maternal and neonatal outcomes in PPROM, and so AFI≤40mm can be used as pregnancy termination threshold to reduce the occurrence of adverse pregnancy outcome.