This research frames student teachers' professional identity formation through the lenses of emotions and dilemmas based on semi-structured interviews and emotional journals. Utilizing grounded-theory analysis method, this paper reveals a pattern of the emotional trajectories that the six student teachers experienced from the beginning to the end of the practicums: eagerness and anxiety at the beginning of the teaching practicums, shock and embarrassment immediately after the student teaching, anger and puzzlement at the middle of the internship, helplessness and loneliness toward the end of the practicums, and guilt and regret after the teaching practice. Furthermore, the participants were faced with four dilemmas: (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 academic performance levels of students. All these dilemmas contribute to the complexity of the teaching practicum in China. Finally, implications for teacher education, especially for preservice teachers' pedagogy of identity and ethical professionalism, are discussed.