This study aims to explore teacher preparation education over the next decade in Taiwan by reviewing previous policy and praxis. Due to the declining birth rate and teacher retirement, balancing teacher supply and demand has become a crucial issue in elementary education. Based on teacher supply and demand models, we selected elementary education as a case example to tackle this issue. Grounded in the notion of balancing supply-demand, this study demonstrates the process of strategy selection in the designed models. The supply side includes enrollment in teacher training programs in terms of capacity of teacher preparations in elementary schools. The demand side includes elementary schools' capacity, which can reflect if the demand for teachers is decreasing or increasing. Autoregressive integrated moving average and transfer functions were used to build the fittest models to predict the capacities of teachers and teacher preparation programs for elementary education. The results reveal that the teacher preparation programs should be remodeled to take account of the declining birthrate. Even so, the preparation system will still have an oversupply of teachers due to the shrinking requirement for elementary education. This study proposes adjusting the student-teacher ratio following our predicted values, as a tool for policy intervention, to provide more reasonable balancing logic of teacher supply and demand for elementary education. The proposed models may provide examples for exploring the complicated issue of future teacher supply and demand.