English is being used as a medium of instruction (EMI) for delivering science lessons in China. This study investigated Chinese high school international programme students' perceptions of and attitudes towards EMI, particularly about their perceived difficulties and support in learning. A questionnaire with Likert-type items, student group interviews, and individual teacher interviews were used in the study. Quantitative data were analysed using confirmatory factor analysis and descriptive analysis, while qualitative data were analysed by means of thematic analysis. The findings indicated a mismatch between the difficulties students encountered and the support teachers provided and revealed the problem of passive strategies for teaching science in English. Findings also suggested strategies for supporting students to learn science in the English medium, especially in inquiry-based science classrooms. These findings have important implications for integrating science and English learning.