To explore the impact mechanism of principals' transformational leadership on students' modernity, this study adopted the structural equation model to test the multiple mediating effects of school climate, teacher quality, and effective teaching on the relationship between principals' transformational leadership and students' modernity. Results showed that there was a positive correlation between principals' transformational leadership and students' modernity; school climate, teacher quality, and effective teaching fully mediated the relationship between principals' transformational leadership and students' modernity, totally accounting for 64.37% of all the indirect effects; the mediating effects of school climate, teacher quality, and effective teaching, respectively, accounted for 30.20%, 52.29%, and 17.51%. According to these results, principal should adopt the approach of transformational leadership, promote the constructing of a fair, inclusive and innovative school climate, emphasize the improvement of teachers' social, emotional, and innovative qualities, and encourage teachers to reflect their teaching and conduct rational practices to improve students' modernity.