Based on an action research study， this paper explored the role of the teacher in the development of learner autonomy and approaches that teachers used to intervene into students' development of learner autonomy in the College English teaching environment． Through the comparison between the self-access learning mode and the classroom teaching mode and the analyses of the intervention effects， this paper found that: 1) the teacher is the construct of learner autonomy in the College English teaching environment; and 2) teachers' intervention through action research helped develop students' language autonomy． Implications for programs that aim to promote learner autonomy are discussed accordingly．