Metaphors are powerful windows to gain insight into EFL teachers' professional identity constructions. This study examined 33 Chinese EFL student teachers' (STs) self-generated metaphors about teaching before and after their student teaching. Before their teaching practicum experience, they were: (a) optimistic, but had naïve perceptions about their roles, (b) worried about their inadequacy to teach professionally, and (c) anxious about their relationship with cooperating teachers. Post-practicum, we noted (a) increased transformative perceptions about their role, (b) professional knowledge growth, (c) the participants explicated a broad array of challenges of building good student relationships, and (d) the placement-school contexts exert a significant influence on their identity formation. Implications for facilitating EFL student teachers' professional identity (trans)formations during the field experiences are discussed.