Abstract: in interacting with each other, human beings can not be separated from the language. In the
bilingual and multilingual societies make Indonesian people are able to speak at least two languages.
Code-mixing is the result of language contact, it happens in learning of Bahasa Indonesia. The
purpose of this study was to describe the background, functions and forms of code-mixing in learning
interactions in SMA Negeri 3 Banjar in the academic year of 2015/2016. This type of research is
qualitative descriptive study. These research subjects is Bahasa Indonesia teachers who teach in the
class of XI, held in the second semester of the academic year of 2015/2016. Analytical Technique
with qualitative-interactive methods. The results of this research, it was found mixed code that
appears in the form of: (1) Background of code mixing in learning internally, due to the use of words
commonly used, avoiding the ambiguous meaning of the word, and use the word in the same
meaning; while externally to indicate a specific meaning, social status and limited vocabulary, (2)
forms such as: words, phrases, clauses, looping words and phrases, (3) Function of skills in the form
of speech teacher in the meaningful of pragmatic declarative, pragmatic interrogative and pragmatic
imperative. Code-mixing in learning of Bahasa Indonesia can be used, with a view to support the
communicative function, so that the material presented can be received and attracted the students.