When people are infected with Mycobacterium tuberculosis, a few of them with low immunity or repeated high-dose infection in a short time will develop signs and symptoms instantly. While some people may clear the infection by their own immune system, most of them will enter a long latent period. About 5%-10% of LTBI will develop into active tuberculosis in a lifetime. Therefore, persistent latent infection in the population is the main source of active tuberculosis. In 2015, the World Health Organization (WHO) announced that the global tuberculosis patients had exceeded AIDS, reaching 10.4 million. Tuberculosis has become one of the world's top ten causes of death. Foreign research shows that a 60-90% reduction in onset rate in high-risk latent infection can be realized through preventive treatment. It is a direct and important mean to reduce the onset rate, as well as an important part of the national tuberculosis prevention and control strategy in Europe and the United States. Considering the signs and symptoms of LTBI, poor protection efficacy of BCG vaccination, and slow reduction in global incidence of tuberculosis (1%-2% annually), WHO issued some guidelines in 2014 to urge more than 130 countries (including China) to carry out LTBI screening and prevention for high-risk population groups. These middle- and high-income countries have a tuberculosis incidence of less than 100 in 10 million. However, China has not yet developed corresponding strategies and national guidelines. It is difficult due to a lack of data on the incidence and characteristics of LBTI, the definition of high-risk population, and intervention studies.