Peer couching is the importance mechanism of educational teaching practice in Taiwan. It reveals the outcome of student teacher's teaching professional development This paper adopt Lortie's view on teachers' goals in terms of their sentiment. Eleven elementary student teachers were chosen for interviews and observations so as to investigate their purposes in the processes of peer couching. The finding of the study was that the purposes of those interns could be conceptualized as four stages from a time frame including marketing-oriented goal for subject-matter chosen, joyfulness in curriculum design for kids, craft pride for demo and criteria of outstanding peers. According the properties of the student teachers' purposes, the reflection on teacher education was provided in the last.