The difference between the social expectations and analyses of teachers’ role and what has been identified by the teachers themselves has been an important cause for the “professional agony” felt by the teachers in their professional practice. This paper tries to explore a teacher’s critical role and its tension in teaching practice by discussing the nature of classroom teaching. It suggests that a teacher should play the role of an dialogist in the complex teaching context by which s/he is better able to create a positive foreign language learning environment, improve teaching efficiency and meet the multiple challenges from the objective world, the students and the self in order to carry on the dialogues in life through classroom teaching.