This article aims to study the dynamic change of teachers’ beliefs among pre-service teachers. A longitudinal design was adopted to investigate English language teaching (ELT) pre-service teachers’ belief change after a 3-month teaching practicum by administering pretest and posttest questionnaires, semistructured interviews, and reflective journals. Repeated measures and paired sample t-test analyses showed significant differences across different aspects of beliefs in all the participants, but belief changes were significant after the practicum only within the experimental group, particularly in the aspects of student management, teaching evaluation, and student learning. In contrast, belief changes were not significant within the control group. Further inductive content analyses of semistructured interviews and reflective journals from the experimental group confirmed these changes and conclusively revealed some potential factors contributing to the changes. The results shed light on how pre-service teachers evolve in their career development and help educators adjust appropriate education policies to improve the quality of English teacher education, particularly in the Chinese context.