This study aimed to explore the experiences of Chinese EFL doctoral students in constructing their academic identities through critical argumentation in their thesis writing in an English as a Medium of Instruction (EMI) context. Data were collected through semi-structured interviews and document analysis. Narrative analysis was used to examine participants' thesis writing to gain insights into their experiences of academic identity construction. The results revealed that Chinese EFL doctoral students face challenges in developing a critical voice and authorial position, synthesizing multiple sources, and positioning themselves rhetorically in their writing. Furthermore, the results open possibilities for a broader understanding of academic writing that values international graduate student's educational background and cultural diversity in target English language discourse communities. While the narrative inquiry study on Chinese EFL doctoral students' academic identity construction through critical argumentation is insightful, there are several limitations to consider, mainly due to the small sample size of only two female Chinese respondents.