In the 21st century, the incidence of preterm birth has continued to increase. According to statistics, preterm birth accounts for 5%–18% of all births worldwide, and 70%–75% of perinatal deaths are related to preterm birth. Preterm birth is not only a cardiopulmonary defect for the baby, but also has a negative impact on the mother's health. Many studies have shown that vaginal microecological dysbiosis-related diseases are the most common causes of preterm birth, such as bacterial vaginosis (BV), vulvovaginal candidiasis (VVC), group B streptococcal (GBS) infections and other infectious diseases. Therefore, we have a review of the deeper understanding of the links and mechanisms between vaginal microecological dysbiosis-related diseases and preterm birth. In addition, timely restoration of vaginal microecology through microbial therapy become the key to prevent and reduce the incidence of preterm birth.