Transnational migrant students have been found to experience marginalization in educational contexts around the world. This critical sociolinguistic ethnography explores the incorporation and learning outcomes of an as yet under-researched group: transnational migrant students from Myanmar in a border high school in China. This context is unique in that migrant students are celebrated as part of China's soft power project to extend its international reach. Despite these welcoming discourses of diversity, transnational migrant students experience significant exclusion as a result of practices such as military-style school regulations, a Gaokao-centered curriculum, and streamed segregation. Overall, the paper highlights the necessity to pay attention to the ways in which schools reproduce social stratification of migrant students through implicit and explicit institutional practices despite celebratory diversity discourses.