Abstract: Embryo transfer (ET) technology is Embryo transfer (ET) is one of the core technologies of contemporary treatment of infertility. At present, the clinical pregnancy rate of ET is only 29.7%-43.4%. The success rate of embryo transfer is affected by many factors, and reproductive tract infection is one of those factors. The reproductive tract microbiome is one of the important micro-ecological systems of the human body. It forms a mutually-restricted and coordinated micro-ecological balance between the host and the environment, and plays a key role in maintaining female reproductive tract health. By evaluating the microecological status of the genital tract before ET, the risk factors of genital tract diseases can be found in time, and the success rate of ET can be improved. The mechanism by which the reproductive tract microbiome affects the success rate of embryo transfer may be related to the abnormal inflammation and immune response caused by changes in the colonic flora of the uterine cavity, which in turn affect endometrial receptivity. The research progress in the application of reproductive tract microbiology in embryo transfer was reviewed in order to provide a new direction for improving the success rate of embryo transfer.

Key words: Microbiota；, Reproductive tract infections；, Infertility, female；, Fertilization in vitro；, Embryo transfer；, Endometrium