The study reported in this thesis concerns about students’ affective problems and the researcher is interested in the causes of non-English majors’ affect in classroom interaction. The conceptual framework of the study has been formed under the influence of a number of important theories of psychology, SLA and pragmatics, the main ideas of all of which are reviewed in the thesis.Based on the theoretical review, this thesis, using questionnaire and interview, intends to find out (1) What attitude does the student hold toward oral English? (2)What inspires or impedes the student’s motivation to speak English, and how strong is the motivation? (3)How much does the student care about his/her self-esteem in classroom interaction and what are the causes of it? (4)Do many students experience anxiety in classroom interaction? If so, where does the anxiety come from? 249 students from differential majors were administered the questionnaire on the causes of students’ affect in classroom interaction. The questionnaire involves 8 factors such as attitude, motivation, self-esteem, anxiety, classroom activities, task, teaching methods and teachers’ characteristics and their oral English levels. The researcher also interviewed six teachers. They talked about their teaching methods, their opinions on students, classroom activities and their personalities. Lastly, these data were processed and analyzed using SPSS 10.0. The results show that although most of students desire to learn and grasp oral English proficiency, because of poor English basis, weak persistence, improper belief toward oral English learning, poor classroom management, some teachers’ low qualities as well as the influence of improper teaching methods, students have negative affect in classroom interaction. Based on the findings, recommendations for more productive and humanistic teaching and educational design and practice are provided for EFL teachers and students in China.