Plague is a virulent infectious disease of natural origin caused by Yersinia pestis, a short, gram-negative bacillus, not a virus. The survival time of S. typhimurium is related to the environment in which it lives, and the length of survival time varies from environment to environment. The survival time of S. typhimurium is longer in low temperature and organism, about 10-20 days in pus and sputum, weeks to months in cadaver, and more than 1 month in feces. B. pestis is sensitive to light, heat, dry environment and general disinfectants. It can be killed by direct sunlight for 4-5 hours; it can be killed by heating at 55℃ for 15 minutes or 100℃ for 1 minute; it can be killed by using 5% carbolic acid, 5% lysol, 5%-10% chloramine, etc. Therefore, through the characteristics of plague bacillus which is afraid of light, heat, dryness and disinfectant, it can effectively kill plague bacillus and reduce the possibility of being infected.