This study applied the Hierarchical Linear Model to analyze the changes in student teachers’ teaching willingness in three years. A total 132 student teachers completed six rounds of surveys in their fourth year of college, during their internship, a semester after their internship, and a year after their internship. A piecewise linear growth model was utilized to analyze the effects of different teacher training channels on the growth rate. The effect of“interaction with the mentor” on the growth rate is included in the second stage after the internship. The research results do not show differences in student teachers’ teaching willingness between their fourth year of college and their internship, while a downtrend appears during the three semesters after the internship. Furthermore, student teachers majoring in education show higher teaching willingness than student teachers not majoring in education in the fourth year of college; however, after their internship, the teaching willingness of student teachers majoring in education was largely reduced. In addition, the consistent opinions of mentors and internship environments with higher structure and moderating effects would slow the decreasing trend of teaching willingness after internship. According to the above research results, relevant suggestions are further proposed in this study.