This paper draws on a case study conducted in a Chinese university in the context of national College English reform. The aim is to investigate the policy enactment of the latest College English reform in China and the interaction between national policies, institutional policy, and teacher agency in responding to this educational reform from an activity theory perspective. The analysis examines the tensions and contradictions within and between the macro policy initiation level, the university implementation level, and the teacher's classroom level, as well as examining the power distribution between these three activity systems. Data were collected from classroom observation, interviews, and examination of reform policy documents and analysed by Critical Discourse Analysis (CDA). The findings suggest that the control-compliance model functioned as the rule for the curriculum implementation at both national policy and institution level. However, in such a restrictive context, the participant teacher's agency was enhanced through her engagement with the research and reflection on teaching, even exceeding the expectations of the reform.