Abstract: This article at first briefly covers the necessity and characteristics of student-centered college English teaching model.Then on the basis of the theory of cooperative principle and politeness principle in discourse analysis,the article conducts a detailed analysis on the main principles of teachers' discourse during the process of their adjusting to the student-centered teaching model.The author aims to find a proper way to improve the college English teaching model from the perspective of discourse analysis and to be helpful for foreign language teachers to achieve their goal of developing the practical ability of students in college English.