Teacher Preparation Law has played an important role in the development of Taiwan's teacher education. Since the enactment of Normal School Law in 1932, Teacher Education Law in 1978, to Teacher Preparation Law in 1994, the legislative history reveals not only the developing process of Taiwan's teacher education system, but also the transformational process of Taiwan society from "monistic, close and regulated" to "pluralistic, open and liberal". The series of recent media reports of unqualified teachers, teacher retirement, educational practicum and internship, teacher recruitment, educational reform can be traced back to the unsolved problems of Teacher Preparation Law. This essay aims to discuss the historical background, legislative significance and practical effects of Teacher Preparation Law by concerning documents, implementation and the co-author's personal experience. This paper seeks to resolve the current problems of Teacher Preparation Law and proposes possible reform of teacher education.