In general, there are a large number of non-pathogenic microflora, called normal microbiota, which exist in symbiosis with the human body and vagina. The female vaginal microecological system consists of the microflora in the vagina, its anatomical structure, the endocrine regulation and immune function of the body. The normal microbial community in the vagina of healthy women is mutually regulated and coordinated with the host and the environment. Current studies have concluded that clinically diagnosable and unexplained vaginal inflammatory diseases all have varying degrees of vaginal microecological dysbiosis. Therefore, maintaining microecological balance has become crucial in the prevention and treatment of reproductive tract infections. A review of issues related to vaginal microecology and female reproductive tract infections is presented. Factors affecting vaginal microecological balance include vaginal pH, changes in flora at different times of a woman’s life, fluctuations in the menstrual cycle and use of sanitary products during menstruation, sex hormone levels, effects of sexual intercourse including pH of semen or lubricants and frequency of intercourse (vaginal pH does not return to normal within 8 h after intercourse), pregnancy, childbirth, contraceptive devices, immunosuppressive drugs, antimicrobial drugs, radiation, etc. inhibitors, antibacterial drugs, radiation, reproductive tract surgery, anemia, hypothyroidism, and infectious factors. In Beijing, Qinping Liao suggests that a comprehensive evaluation of the vaginal microecological environment should be performed by describing the morphological aspects of the vaginal flora such as density, diversity, predominant bacteria, inflammatory response of the organism and causative bacteria, combined with functional indicators such as vaginal pH, hydrogen peroxide and leukocyte esterase. Abnormalities in any of the above indicators can be diagnosed as microecological disorders. Vaginal pH and flora status is one of the most important indicators of vaginal microecological changes. In women of reproductive age with normal menstrual cycle, vaginal pH is 3.8-4.2 in the absence of vaginal infection. pH changes are more sensitive in the diagnosis of lower genital tract infections. Ovarian function affects vaginal microecology Ovarian estrogen secretion directly affects the proliferation of vaginal mucosal epithelial cells and influences vaginal pH, cleanliness and the proportion of Lactobacilli. During sexual maturity, the level of estrogen is on the rise and the vaginal mucosal epithelial cells have increased levels and more glycogen stores, with Lactobacillus as the dominant bacterium, thus providing strong resistance to pathogens. With the increase of age and the decrease of ovarian function, the vaginal mucosal epithelial cells are mainly in the bottom layer without glycogen, which leads to the gradual increase of vaginal pH and a significant decrease of Lactobacillus, the dominant group of vaginal flora. Vaginal immune function is a component of systemic immune function, including humoral immunity and cellular immunity.1. Vaginal non-specific immunity against infection. The intact vaginal mucosa can effectively prevent the invasion of fungus and other microorganisms and play its role as a mechanical barrier.2. Specific immunity of the vagina against infection. At present, there are some misconceptions and irregularities in the diagnosis and treatment of reproductive tract infections, such as not treating the pathogens and the treatment plan is not uniform; using a variety of mixed drugs, although there are drugs for the pathogens, but the amount of drugs is not enough; not paying attention to personal hygiene and sexual hygiene; not paying attention to the regular review and follow-up after the use of drugs and various factors related to vaginitis; neglecting to adjust the vaginal ecological environment and over-treatment The problem of vaginal ecological balance is disrupted by vaginitis. The vaginal microecology theory provides a new treatment concept, that is, the transition from the previous concept of killing microorganisms to increasing probiotics and restoring the normal vaginal microecological environment.