英语教学课程中的语码转换使用情况曾是很多研究者探究的热衷问题。这些研究中诸多都是研究教师话语中的语码转换情况。然而，实习老师作为一种特殊的教育群体，他们在课堂上也会使用语码转换。实习工作作为免费师范生上岗前权威的一次训练，在实习老师的教学工作中起着非常重要的作用。实习老师需要从实习工作中不断地总结经验，才能更好的从中获取更多的知识。但是免费师范生就职前两个月实习工作中的相关研究到目前都是空白的。因此，本研究试图研究实习老师在英语教学课堂中的语码转换情况。 本研究通过三种渠道搜集资料：观察录像课堂，问卷调查及对实习教师进行采访，之后运用定量及定性的方法对搜集的语料进行分析。本文的研究对象是来自北京师范大学的都具有实习经历的60位免费师范生。通过对三名实习老师的九个录像课程的转写和研究分析问卷调查及对实习教师的采访，本研究对实习教师在英语教学课堂上使用语码转换的现状，包括实习老师使用语码转换的百分比里，使用语码转换的频率分布，对使用语码转换的态度等等有了基本的了解。主要发现为：第一，实习老师对课堂语码转换的使用情况的态度差别较大，其导致的因素有：地理位置因素、教学年级不一致以及最主要的学生能力因素。第二，90%的实习老师在课堂教学中使用语码转换，其中70%的实习老师同意在课堂上使用语码转换的概念。还有其他20%的实习老师虽然不同意在课堂上使用语码转换，但在实习课堂当中也会使用语码转换。第三，实习老师在课堂中使用最频繁的是句中语码转换，主要用于课堂词汇教学当中。讲解语法知识是实习老师在课堂上使用语码转换的主要功能，有76%的实习老师在讲解语法知识的时候，使用语码转换。第二主要的功能为翻译重点词汇和难点句子。

Code-switching in English class is a hot topic for many researchers. Many studies on code-switching focus on the teachers. While the university students who work as student teachers in school also use code-switching in their classroom. The period of teaching practice in real classroom is perhaps the most significant for the student teachers before they get their own jobs as teachers. However, the research about student teachers’ use of code-switching is blank. In order to meet the gap, this research aims to study the code-switching in student teachers’ classrooms. This study uses three methods to collect data: classroom observations, questionnaires and interviews of the student teachers. The subjects of this research are 60 students who worked as student teachers for two months from a teacher training university. This research analyzed the questionnaires and the transcript of three student teachers’ nine classes and the interviews. There are three main findings from the study. First, the attitudes towards code switching among student teachers’ vary, which is caused by several factors, like school factors, difference in teaching grades and most commonly the students’ ability. Second, 90% of the student teachers use code-switching in classroom and among them 70% agree with the idea of using code-switching. The other 20% of the student teachers use it although they keep negative attitude towards code-switching in classroom. Third, intra-sentential code-switching is used mostly among the student teachers, which is widely used in vocabulary teaching. About 76% of the student teachers use code-switching when explaining the grammar knowledge, which is the most needed function of it, next to which is the translating the key and difficult sentences.