English for medical purposes is one of the most significant ESP sub-topics, and an increasing number of studies have focused on the English teachers, English teaching and learning in medical universities. However, these studies were rarely designed to explore the medical English teachers’ teaching beliefs and practical teaching practices against the background of ESP curriculum. To figure out the theoretical confusions and operational difficulties of medical English teachers on the way to ESP teacher development, this qualitative study tends to explore 4 English teachers’ teaching beliefs and practices about ESP in a key medical university in China. Data was collected from multiple sources, that is, classroom observation, semi-structured interview, teaching plans, students’ homework, teachers’ reflections and the like. Data analysis showed that teachers believed ESP was the guideline for their teaching but they lacked of enough training on ESP teaching and subject knowledge. They also believed that ESP should be well integrated with EGP and that EGP was the basis for ESP. Their practices were generally consistent with their practices. These findings would provide some directions for fellow teachers’ teaching and researchers.