Nowadays,in China,English speaking class lacks of interaction and the students seldom have opportunities to practice English.Interactive teaching model should be introduced to the class.This paper discusses the significance of the interaction,which indicates that the interaction is the process of communicating the ideas and feelings and affecting each other.And then it analyzes the theoretical basis of the interactionteaching mode.In the process of interaction between the teacher and students,CAI is a good means to encourage students to open their mouths.In this paper,some tips of applying CAI are also suggested.