Through a case study, this study explores four MTI supervisors' beliefs and practices in graduation thesis supervision. The results indicate that their beliefs in the forms, topics and revision of graduation theses basically conform to the MTI program's overall objective of cultivating translation practitioners, with due attention to students' academic English writing competency. The supervisors' supervising practices are largely consistent with their beliefs, while certain beliefs could not be applied to practices. An Activity Theory analysis shows that when such units as the subject, rules, community and division of labor conflict with the supervisors' beliefs, their practices will deviate from beliefs. The paper further provides some implications for the future development of the MTI program in China.