Objective: To explore the effectiveness of preventive treatment for latent tuberculosis infection (LTBI) patients, so as to provide reference for the management and preventive treatment of clustered epidemic in schools. Methods: Data came from the school tuberculosis outbreak of a boarding high school in Kaizhou District, Chongqing, which occurred between June 2017 and March 2018 among 2016 grade high school teachers and students for investigation and analysis. The total incidence, LTBI patients, and the incidence after preventive treatment for 5 years were followed up. Results: A total of 34 cases of pulmonary tuberculosis from June 2017 to March 2018. A total of 1 357 individuals were screened for 6 concentrated contact screenings, with a confirmed tuberculosis rate of 2.43%, a tuberculosis skin test (TST) positive rate of 27.41%, and a strong TST positive rate of 7.39%. Among them, the confirmed tuberculosis rate and TST positive rate in the first case class were much higher than those in other classes, with statistically significant differences ( χ 2=286.30, 98.59, P ＜0.01). 88 cases of LTBI were found, with 31 cases receiving preventive treatment (35.23%), of which 28 completed preventive treatment (90.32%). After five years of follow-up, 73 cases of pulmonary tuberculosis were diagnosed in 2016 by the school senior high school, with a incidence rate of 0.98/10 2 (person/person years). Fifteen of the 88 LTBI patients were diagnosed with pulmonary tuberculosis, and the incidence rate was 3.33/10 2 (person/person years). The incidence rate of the preventive treatment group was 0.7/10 2 (person/person years)lower than that of the medical observation group 4.5/10 2 (person/person years), with a statistically significant difference ( χ 2=4.31, P ＜0.05). Conclusion The classes with higher TST positive rate and strong positive rate have higher incidence rate. Improving the preventive treatment rate of LTBI patients can effectively reduce the incidence rate of tuberculosis.