Abstract： Objective To investigate the vaginal flora characteristics,clinical symptoms and signs of lactating women 6-8 weeks after delivery and the influence factors.Methods Two hundred and twenty-three puerpera 6-8 weeks after delivery who went to outpatient department of Peking University First Hospital for postpartum review (study group) and 200 normal non-pregnant women (control group) from April to May,2010 were enrolled into this study.All in study group were evaluated by a questionnaire regarding their symptoms,sexual behavior,breast-feeding situation and delivery mode.Vaginal secretions from upper 1/3 of vagina were collected and evaluated by vaginal microbial evaluation system.Bacterial vaginosis (BV) was diagnosed if Nugent score ≥ 7.Enumeration data between groups was compared by t test,and quantitative data by Chi-square test.Results The density of vaginal flora in study group was different from that of control group (x2 =96.302,P＜0.001) ; so did the flora diversity of two groups (x2 =69.871,P＜0.001).There was no difference between mean age of study group [(30.5 ± 3.9) years] and control group [(30.9 ± 2.4)years],P＞0.05.The cesarean section rate was 52.7％ (89/169),13 women (7.7％) had began their sexual behavior before interview,116 women (70.3％) took breast-feeding.Dominant bacteria in the vagina of lactating women were Gram-positive cocci (69/175,39.4％) and Gram-positive bacillus (54/175, 30.9％), which was different from control group (Gram-positive bacillus,180/189,95.2％),P＜0.001.The vaginal pH of study group was 5.0±0.5,which was higher than that (＜4.5) of control group.In study group,incidence of lower hydrogen peroxide level of vagina was 84.3 ％ (177/210) ; positive rate of sialidase was 6.7 ％ (14/210) ; positive rate of leukocyte esterase was 91.0％ (191/210).A large number of postpartum women had an abnormal Nugent score,most of them showed a state of intermediate BV (132/195,67.7％) or BV (8/195,4.1％),while a few patients had symptoms of BV (23.5％,33/140).Sexual behavior had no significant effect on postpartum vaginal flora.The proportion of abnormal vaginal flora in breast feeding mothers (74.1 ％,86/116) was significantly higher than that (57.1％,28/49) in artificial feeding mothers,P=0.034.Delivery mode also affected postpartum vaginal flora.Women underwent cesarean section were more susceptible to abnormal vaginal flora (77.5％,69/89) than those underwent vaginal delivery (57.5％,46/80),x2 =7.726,P=0.005.Conclusions Vaginal flora of postpartum women 6-8 weeks after delivery had significant difference from that of nonpregnant women.The incidence of asymptomatic abnormal vaginal flora was high.Breastfeeding and delivery mode are influence factors of abnormal vaginal flora.