Bacterial vaginosis is not caused by a single bacterium, but by a combination of pathogenic bacteria. The ecological balance of bacteria normally found in the vagina is imbalanced, resulting in a mixed bacterial infection with mainly anaerobic bacteria, the concentration of which increases to 100-1000 times that of normal women. The anaerobic bacteria proliferate and produce amines at the same time, resulting in increased vaginal discharge and odor. The typical clinical symptoms are milky vaginal discharge with fishy odor. 2. Gynecological examination of the vagina and cervical mucosa is not congested or red and swollen, and leucorrhea is increased. The diagnosis of bacterial vaginosis is based on 4 aspects: (1) Vaginal discharge is milk-like, homogeneous and smelly. (2) Vaginal pH > 4.5. (2) Vaginal pH > 4.5. (3) Positive amine test. (4) Positive clue cells (> 20 %). The clinical diagnosis can be made by three of the above four positive tests, of which the fourth one is the gold standard for diagnosis. Treatment principle: Treatment is based on local medication such as anti-anaerobic drugs. 1, systemic drugs for the first treatment preferred metronidazole 0 . 4g , Bid, continuous for 7 days; or metronidazole 2g, single oral; lincomycin 0 . 3g, Bid, for 7 days. 2.Topical medication 2% lincomycin ointment, vaginal, Qd, 7 days; or metronidazole effervescent tablets, qd, 7-14 days; sexual partners do not need routine treatment. 3, treatment during pregnancy for any symptomatic pregnant women and asymptomatic women with high-risk pregnancy (such as premature rupture of membranes, history of preterm delivery) must be examined and treated, mostly with topical medication. Metronidazole is used as above.