Objective: To analyze epidemiological trends and changing characteristics of syphilis among students in Yunnan Province from 2005 to 2023, so as to provide evidence for the comprehensive prevention and control of syphilis in schools. Methods: The case data of syphilis among students in Yunnan Province from 2005 to 2023 were obtained from the China Information System for Disease Control and Prevention. The Joinpoint regression model was used to conduct a time trend analysis of the reported incidence rate of syphilis. Results: From 2005 to 2023, a cumulative total of 3 191 cases of syphilis were reported in schools in Yunnan Province(1 248 male cases and 1 943 female cases). The reported incidence rate rose continuously from 0.17/100 000 in 2005 to 8.26/100 000 in 2023, with an average annual percent change (AAPC) of 24.89%( Z =13.18, P <0.01). The reported incidence rate was higher in female students than in male students ( χ 2=229.48, P <0.05). The incidence rates in the primary school, junior high school, senior high school and higher education were 0.21/100 000, 2.42/100 000, 4.45/100 000 and 6.29/100 000 respectively, and the difference was statistically significant (χ 2=3 432.84, P <0.05). The average annual growth rate was the highest in the junior high school stage(AAPC= 30.68% , Z =7.57, P <0.05),followed by the senior high school stage (AAPC=24.28%, Z = 5.70 , P <0.05).The reported incidence rate of primary and secondary syphilis increased from 0.12/100 000 in 2005 to 2.06/ 100 000 in 2023, with an AAPC of 16.86% ( Z = 4.57, P <0.05). Conclusions The overall reported incidence rate of syphilis among students in schools in Yunnan Province shows a sustained upward trend, with the most rapid annual increase observed in junior high schools. Schools should prioritize syphilis education and expand awareness campaigns to curb transmission.