Objective Through the investigation and analysis of a school tuberculosis cluster epidemic in Huoshan County,the reasons for the school tuberculosis cluster epidemic were explored,and the basis for improving the prevention and control of tuberculosis in schools in Huoshan County was provided. Method Close contacts of the index case were screened by field epidemiological methods and the relevant data were analyzed. Results A total of 3 cases of students with tuberculosis were screened out,of which 2 cases had obvious epidemiological correlation with the index case and were identified as a cluster epidemic.The index case is the first case.The class of the first case (Class 18,senior 3) had a strong positive rate of 26.1% in the Purified Protein Derivative of Tuberculin (PPD) skin test.The strong positive rate of tuberculin skin test of students in adjacent classes on the same floor (Class 16,senior 3) was 11.0% (7 / 66).There was significant difference in the strong positive rate of PPD between the two classes(χ²=5.358,P=0.021).The PPD positive rate was 16.2% (6 / 37) in male students and 37.5% (12 / 32) in female students about the class of the first case,the difference was statistically significant(χ²=4.031,P=0.045). Conclusion The first case is infectious.Delays in detection were the main cause of the cluster outbreak.To do well the preventive medication intervention work of close contacts of the first case can block the occurrence of the cluster outbreak.