本文旨在从社会语言学观点出发研究大学英语教学中的语码转换现象。我们从课堂获得第一手资料,通过分析获知大学英语教学中教师进行语码转换主要有四类动机,即,话题转换,情感功能,社会性功能和重复功能。随后对大学外语教学中语码转换应遵循的原则我们也进行了一些探讨。 This article aims to study the phenomenon of code-switching in college English teaching from the perspective of social linguistics. We learned from the classroom first-hand information, through the analysis of college English teachers learn the code-switching there are four main motivations, namely, topic conversion, emotional function, social function and repetitive functions. Then we also carry out some discussions on the principles that code-switching should follow in college foreign language teaching.