Learner identity has been recognized as significant for second or foreign language learning in the recent decades. By employing Bamberg et al.’s (2011) framework of three identity dilemmas and Norton’s identity theory of SLA (Norton, 2000, 2010) as the theoretical foundation, this study investigates how learners’ identities transformed, and how they were related to learners’ English learning trajectories by tracing a group of first-year English majors in a key university in China for one year. With the data elicited from one of the participants’ diary and in-depth researcher-participants meetings, this paper suggests that English learning is not just a process of acquiring a set of language skills and knowledge, but a complicated social practice, in which learners’ identities are constantly constructed, deconstructed and reconstructed. This finding has important implications for English teaching and learning in China.