Mycobacterium tuberculosis can survive on the surface of objects for a few days to a few months, and the survival time of Mycobacterium tuberculosis on the surface of objects is affected by the ambient temperature, humidity, ultraviolet rays and so on. Mycobacterium tuberculosis adhering to dust can remain infectious for 8~10 days, and can survive for 6~8 months in dry phlegm; Mycobacterium tuberculosis can survive for several months in dark and humid places indoors, and Mycobacterium tuberculosis can survive for several years at minus 40 degrees Celsius. Mycobacterium tuberculosis is more resistant to cold, dryness, acidity and alkalinity in the external environment. Mycobacterium tuberculosis is sensitive to heat and humidity, and can be inactivated by heating in liquid at 62-63 degrees for 15 minutes. It can be inactivated in two minutes in 70% ethanol. To prevent the transmission of tuberculosis, it is necessary to exercise and increase the resistance to disease. To prevent the transmission of tuberculosis bacilli, wear a mask and be aware of prevention to avoid adverse results.