This study explores the perceptions of Chinese engineering-major students towards their English learning experience after taking a mandatory English composition course in an EMI college. The investigation centers on first-year students' perceptions of transitioning to EMI, with a focus on how the composition course has assisted students' transition as a primary language support. Data were collected through a metaphor elicitation technique in which students expressed their perceptions of English learning, complemented by a thematic analysis of 86 reflection essays on the composition class. An analysis of the 334 metaphors identified students' enhanced confidence in English, the importance of the English-using environment, positive views of learning communities, and increased agency in the learning process. It also revealed that many students were stressed and unaware of learning strategies, therefore suggesting institutional-level language support. One implication is to promote the culture of the learning community. The findings can be particularly useful for programs that are implementing language support for non-English major students.