Lexical bundles, as building blocks of discourse, play vital roles in helping members from the same academic community achieve successful communication and disseminate sustainable disciplinary knowledge. However, little attention has been paid to lexical bundles in postgraduate writing. Drawing on Biber et al.’s (1999) structural taxonomy and Hyland’s (2008a) functional taxonomy, we identified and compared lexical bundles in two self-built corpora, an EFL student writing corpus and an expert writing corpus. The results indicate considerable structural differences between the two groups: the student writers used verb phrase-based bundles more frequently and prepositional phrase-based and noun phrase-based bundles less frequently. In terms of function, although the two academic groups showed similar distributions of the three main functional categories, as student writers they exhibited insufficient reader-awareness and incomplete knowledge of stance expressions. It is hoped that the findings will shed light on future pedagogical practices to help novice writers improve their academic writing competence as a sustainable goal in enhancing their academic scholarship.