Over the past decades, increasing interest in code-switching has triggered numerous empirical studies in the foreign language classroom, which show that the switching to L1 has become an important strategy in foreign language teaching and its implication in bilingual classroom is of great importance. This paper is a preliminary endeavor to probe into the situation of the switching to the L1 in Chinese university classes, with a focus on revealing how much the L1 is used in different lesson contents. Benefiting from the previous studies and practice, this study integrates the qualitative and quantitative research methods to analyze the amount of the L1 use in the three typical lesson contents: theme-based activities, text analysis and discussion of tests and other assignments. The data are collected through the teachers' and students' questionnaires, classroom re- cordings and teachers' interviews. It has been found that the amount of the L1 varies in different lesson contents, that is, least in theme-based activities, then in text analysis and most in discussion of tests and other assignments and this situa- tion is caused by different features of the three lesson contents. By discussing the practical implication of the research in English teaching, it suggests that teachers should consider lesson contents to decide how much the L1 is used in different context and this will consequently lead to better instruction in EFL classroom with an appropriate use of the L1.��