To explore its effectiveness on alleviation of English speech anxiety and improvement of oral English competence, cooperative learning is employed in a college English speaking class. Data is collected through a pre?test?post?test design together with interviews. The changes of anxiety degree and oral English proficiency in both the experimental group and the comparison group are put into statistical analysis. The results indicate that cooperative learning possesses certain affective advantages, which helps to facilitate more communication and mutual assistance among students. As a result, students’ speech anxiety is reduced to a great extent and their oral English is also improved significantly. The study makes in?depth discussions on how cooperative learning makes those changes possible from the perspective of social interdependence theory.