EFL classroom teaching in China, no matter whether it is traditional one or a flipped one, is a dynamic communicative process by using English with the aim of learning it. The interactive discourse between the teacher and the student has its own pragmatic functions, especially the feedback given by the teachers which may influence the teaching and learning efficiency. In order to provide appropriate investigation resources, a corpus of 128,223 words with 36.65 hour-2199 minute real audiovisual college EFL classroom teaching transcripts is built. Taking the data of the resources as supporting evidence, this paper analyzes the pragmatic functions of EFL classroom feedback discourse, and proposes certain pragmatic strategies of increasing interactivity, which has certain pedagogical implications for EFL classroom teaching.