With higher education being more internationalised, English-medium instruction (EMI) and transnational universities have become prominent features of China's tertiary education. However, EMI implementation has faced challenges, with stakeholder perceptions varied. Guided by Bernard Spolsky's (2004, 2009) language policy and management frameworks, the study investigated the lecturer's perceptions of EMI practices, rationale and the policy in one university to reveal the complexity of the interplay between the three-pronged aspects involved in EMI teaching and learning. It highlights the challenges lecturers face due to students' insufficient English proficiency, despite students showing positive attitudes towards EMI, as evidenced by parallel studies on students' perspectives. Meanwhile, a significant misalignment between stated EMI policies and their actual implementation is revealed, raising concerns about the effectiveness and outcomes of EMI in the concerned transnational university.