This research examines the emotional and ethical dimensions of identity shaping in student teachers' teaching practicum. By interviewing seven Chinese student teachers who had just finished their student teaching practice, the research examines the participants' emotional experiences and the ethical dilemmas they encountered in their practicum. Specifically, for the emotional aspect of professional identity formation, the student teachers experienced eagerness and anxiety at the beginning of the teaching practicum, shock and embarrassment once teaching, and guilt and regret towards the end of the practicum. Alongside the influx of emotional experiences in the practicum, the researcher identified four paired ethical dilemmas that the participants were trapped within: (1) tensions between classroom authority and the ethic of caring; (2) acting as a community member or an "outsider"; (3) working as an office assistant or a "real teacher"; (4) conflicting pedagogies regarding teaching different tracks of students. Finally, implications for teacher education are briefly discussed.