The objective of the research is to describe the types of code-switching and to find out the functions of code-switching. The method used in this research was qualitative descriptive. The sample of the research consisted of one lecturer of English Study Program at IAIN Bone. This research focused on the analysis of types and functions of code-switching. In this research, the researcher used the type of code-switching by Poplacks’ theory. Meanwhile, the researcher used Gumperzs’ theory to analyse the function of code-switching. Moreover, to interpret the data gathered, the researcher analyzed them through three steps of analysis by using the mode from Miles and Huberman, they were; data reduction, data display, and data verification. The findings indicated that the types of code-switching are simply found in three types; (a) inter-sentential code-switching (without inserting new information and which inserts new information), (b) intra-sentential code-switching (translation or word/phrase substitution within a sentence), and (c) tag-switching (interactional fillers code-switching). The functions of code-switching used by English Lecturer in the classroom were found for three functions; they are to mark injections or to serve as sentence fillers, to clarify and emphasize a message, and to qualify a message.