The research was conducted to investigate the use of teachers’ code-switching in the process of teaching and learning English as a foreign language at a high school in Yogyakarta. This research aimed to explore teachers’ code-switching in English for foreign language classroom. In addition this research want to find out the factor influencing teachers’ code switching in EFL classroom, and what is the function of teachers’ code-switching in EFL classroom. In this research, the researcher used a qualitative design. This research involved two English teachers from the high school. The researcher interviewed the participant to obtain the data. The finding of this research showed that there are three factors that influencing teachers’ code-switching that is students’ English proficiency, complex material, and teachers’ code-switching as a strategy. and three functions for teachers’ code-switching in the EFL classroom. The finding of this study also showed that there were three function of teachers’ code-switching in English for foreign language classroom. The function were teachers’ code-switching for transmitting knowledge, teachers’ code-switching for classroom management, teachers’ code-switching for emotional relationship.