Objective To analyze the dynamic changes and influencing factors of Mycobacterium tuberculosis (TB) infection in grade-1 students in senior high school at the time of enrollment and one year after enrollment. Methods In 2022, TB screening was carried out among grade-2 students in 4 senior high schools in Binhai and Xiqing Districts of Tianjin. Basic information of students was collected, and TB infection detection results of grade-1 students in senior high school at the time of enrollment were collected retrospectively. Positive rate, strong positive rate and positive conversion rate from tuberculin skin test (TST) results of students were compared. Univariate and multivariate logistic regression models were used to analyze the relevant influencing factors for positive conversion of TST results. Results The overall positive rate of 1 839 students one year after enrollment was higher than that at the enrollment (46.82% vs 33.12%), while strong positive rate was lower (12.51% vs 13.00%), both with statistically significant differences (both P<0.001). One year after enrollment, 64 out of 1 230 students who were originally negative for TST in their first year of senior high school turned positive, with a positive conversion rate of 5.20% (95%CI: 3.93%-6.48%). One year after enrollment, TST results showed that the average diameter of induration was 5 (2, 8) mm, diameter was 2 (0, 5) mm at the enrollment of the first year of senior high school, but the difference was not statistically significant (P=0.478). The difference range of average diameter of induration was ±21 mm, 39.70% of students being within ±2 mm. Students with increased and decreased average diameter of induration accounted for 65.09% and 28.49%, respectively. Multivariate logistic regression analysis result showed that students in boarding school had a higher risk of positive conversion compared with non-boarding school students (OR=4.842, 95%CI: 2.794-8.392). Conclusion The screening of TB infection among grade-2 students in senior high school should be strengthened, with a focus on boarding school students. Early detection of tuberculosis patients and newly infected individuals can provide reference for implementing precise prevention and control.