Abstract： Objective To find out the bacterial species in the vagina of postpartum women and the possible influencing factors on colonization. Methods From Jun. 2007 to Oct. 2007, 560 postparmm women from 7 hospitals in China were enrolled. Questionnaire survey, gynecological examination and Nngent score of vaginal smear and microbial spectrum study of the vaginal flora were completed. Results (1 ) According to the Nngent score, 48 out of the 560 women were normal (8.6%), 337 at the borderline (60. 2% ) and 175 (31.2%) were complicated with bacterial vaginosis (BV). Among the 560 women, Bacterium lacticum were identified in 74 cases (13. 2% ), but not in the rest 486 cases (86. 8% ). Gardnerella and bacteroids were detected in 322 women (57. 5% ) and small flectobacillus in 214 women (38. 2% ) out of the 560 subjects. (2) Influencing factors on vaginal microflora: among the 266 women who had normal vaginal delivery, 23 (9. 4% ) showed normal vaginal microflora, 148 (55.6% ) at borderline and BV was diagnosed in 93 women (35.0%). The corresponding figures among the 294 women who underwent cesarean section were 23 (7. 8% ), 189 (64. 3% ) and 82(27.9% ), respectively. However, the incidence of BV had no statistical difference between these two groups (P = 0. 204). In the 233 women who received episiotomy, 22 (9. 4% ) showed normal vaginal microflora, 135 (57.9%) at borderline and 76 presented with BV (32. 6% ), the corresponding figures among the 327 women without episiotomy were 26 (8. 0% ), 202 (61.8%) and 99 (30. 2% ), respectively. The incidence of BV did not show any statistical difference between the above two groups (P = 0. 790 ). (3 ) Prenatal vaginitis were reported in 46 women, among which 5 (10.9%) with normal vaginal flora, 26 (56.5%) at borderline and 15 (32.6%) with BV, and again in the 514 women without prenatal vaginits, the above figures changed to 43 (8.4%) , 311 (60. 5% ) and 160 (31.1%). No significant difference was found in the incidence of BV between the two groups (P =0. 962). The rate of BV in women without sex, with sex occasionally and with sex frequently during pregnancy was 27.5% (78/284), 35.6% (96/270) and 1/6, respectively (P = O. 185), and the numbers in women who had breast-feeding, bottle feeding and mixed feeding were 31.0% (67/216), 39.3% (35/89) and 28.6% (73/255), respectively (P=0.573). Conclusions The amount of Lactobacillus in vagina of postpartum women is greatly reduced leading to dysbacteria. The incidence of BV is not affected by vaginal delivery, episiotomy, vaginitis, prenatal intercourse and the way of feeding, but is higher in postpartum women.