This research aimed to study 22 elementary school pre-service teachers' attitude change of the transformed course and the contributing factors that facilitates their understanding of the transformed course during the process of curriculum transformation. Data analysis was based on group discussions, lesson plans, teaching drills and interview corpus. This research showed that through the process of curriculum transformation, the pre-service teachers acquired more understanding toward course development and curriculum content; in contrast, peer discussions, reflections on practical experiences, pre-service teacher trainings, the uses of teacher's handbook, and feedbacks from students and teacher-counselors were critical factors to facilitate the development of pre-service teachers' understanding of the mathematics curriculum. Finally, the research proposed relevant suggestions for future mathematics teacher education and research references.