Abstract: Based on the first-hand data of student to student conversation in a college English classroom, this paper explores the pragmatic functions and characteristics of others'repetition in student to student conversation by using discourse analysis as a research tool. It is found that the pragmatic functions of frequent repetition of peer discourse are obvious, including positive response, negative response, positive response, information confirmation and turn taking. On this basis, from the perspective of social cognitive theory, this paper analyzes the causes of its formation, including immediate context coordination, cultural context adaptation and participation tendency. In order to promote the reform of college English teaching and improve the quality of curriculum teaching, we should encourage students to participate in interactive negotiation and classroom participation; participants in task negotiation should have the same level of second language; create a cooperative context and atmosphere; do well in process supervision, guidance and evaluation.