Objective To analyze the effectiveness and effect on pregnant outcome about living preparation of lactobacillus versus metronidazole in the treatment of bacterial vaginosis in pregnancy. Methods We searched PubMed, The Cochrane Library, VIP, CNKI, Wangfang, CBM, FMJS, and FEBMT to identify randomized controlled trials (RCT) of living preparation of lactobacillus versus metronidazole for bacterial vaginosis in pregnancy. The quality of the included trials was assessed. RevMan 5.0.24 software was used for meta-analysis. Results Eight trials involving 1 687 patients were included. The results of meta-analysis showed: no significant difference was found in the effectiveness between the two groups (RR=1.04, 95%CI 1.00 to 1.08, P=0.08); living preparation of lactobacillus had lower recurrence rate and lower premature delivery rate compared with metronidazole (RR=0.16, 95%CI 0.06 to 0.43, P=0.0004; RR=0.56, 95%CI 0.33 to 0.94, P=0.03); no significant differences were found in premature rupture of membrane, puerperal infection, infant of low-birth weight, infant infection, and infant jaundice between the two groups. Conclusion The effectiveness about living preparation of lactobacillus versus metronidazole for bacterial vaginosis in pregnancy is similar, but living preparation of lactobacillus has lower recurrence rate and lower premature delivery rate, the others of effect on pregnant outcome are similar.