BCG vaccine is mainly used to prevent tuberculosis and is also an effective cellular immune booster. Tuberculosis is a common chronic infectious disease that is mainly caused by Mycobacterium tuberculosis attacking human organs. The attenuated live bovine Mycobacterium tuberculosis strain used to prepare BCG vaccine has lost its toxic effect on humans through special artificial culture. However, it retains enough antigenicity to make BCG vaccine one of the commonly used vaccines for the prevention of tuberculosis, and after vaccination it has great benefits for the healthy growth of children, especially for the prevention of diseases with poor prognosis such as childhood tuberculous meningitis and cornual tuberculosis, effectively reducing the mortality rate after the disease. In addition to preventing tuberculosis, the immune-enhancing effect of BCG vaccine can activate the body’s immune-active cells and assist in the treatment of acute leukemia, lung cancer and other diseases, and can also be used to prevent pediatric colds and chronic bronchitis in adults.