Objective：To investigate the distribution and variation of bacterial flora in the vaginal microenvironment of pregnant women with premature rupture of membranes（PROM） through a retrospective analysis，and to provide a reference for the prevention and treatment of PROM caused by infection. Methods：The pregnant women with PROM who were admitted to our hospital from January 2016 to October 2017 were enrolled，with other related complications excluded. The bacterial flora in vaginal microenvironment during rupture of membranes and pregnancy outcome were analyzed. Results：A total of 302 patients were enrolled and divided into PROM group（n=135） and preterm premature rupture of membranes（PPROM） group（n=167）. The vaginal flora of pregnant women with PROM was dominated by G+ bacillus，usually with ureaplasma urealyticum（UU） infection and other bacterial infection. The dominant bacteria in the vaginal discharge of PPROM group were non-G+ bacillus，and showed significantly higher positive rates of UU and other bacteria than the PROM group（P<0.05）. The change in dominant vaginal bacteria had no significant effect on vaginal flora（P >0.05），and the change in vaginal flora had no significant effect on umbilical artery blood pH of neonates at birth（P >0.05）. When the dominant vaginal bacteria were non-G+ bacillus and the flora was inhabited，the transcutaneous bilirubin measurement of neonates aged 24 h was increased. When the dominant vaginal bacteria were non-G+ bacillus with positive UU and other pathogenic bacteria，the transcutaneous bilirubin measurement of neonates aged 24 h could be increased. When the bacterial flora in vaginal microecology was inhibited with positive UU，the transcutaneous bilirubin measurement of neonates aged 24 h could be increased（P <0.05）. Conclusion：Vaginal flora composed of non-G+ bacillus and infection with UU and other bacteria is the high-risk factor for PPROM. The change in dominant vaginal bacteria cannot cause imbalance of other flora. However，the change in dominant bacteria of vaginal microecology and infection with mycoplasma and other pathogenic bacteria can lead to neonatal jaundice.