Bladder cancer is a common malignant tumor of the urinary system. The incidence and mortality of bladder cancer in China have been at a high level. In the past, people generally believed that the bladder was a sterile environment, but it has been found that there are symbiotic microorganisms in the bladder. In addition, microorganisms and their metabolites in urine may be involved in the occurrence and development of various urinary system diseases such as bladder cancer. At the same time, microorganisms and their component products such as Bacillus Calmette-Guerin vaccine play an important role in the treatment of bladder cancer. This article reviews the research progress of urinary tract microorganisms and the occurrence, development and treatment of bladder cancer, and aims to provide new ideas for the early diagnosis and treatment, prevention and prognosis evaluation of bladder cancer.