With 232 preservice teachers as research subjects, the present study analyzed the growth trend of teacher belief and the effect of teaching willingness on the initial state and growth trend of teacher belief during practical training. The research survey was conducted three times in one and a half years. An analysis of the hierarchical statistics revealed the following: (1) Preservice teachers’ teacher belief comprises four dimensions, namely student discipline, curriculum and teaching planning, teaching and evaluation, and student learning, all of which present a linear downward growth trend. (2) Teaching willingness exerts effects on the initial state of teacher belief. (3) Teaching willingness appears to negatively moderate the growth trend of curriculum and teaching planning and teaching and evaluation. In other words, preservice teachers with higher teaching willingness exhibit a slow declining trend of curriculum and teaching planning and teaching and evaluation. According to the analysis results, the paper propose relevant suggestions for education institutes/teaching practitioners and suggestions for future research.