Language complexity has been proposed as a valid and basic descriptor of L2 performance, and as an index of language development and progress. With the assistance of L2SCA, the present corpus-based contrastive study aims at analyzing the linguistic features of theses abstracts written by foreign Masters and Chinese Masters. It is found that with respect to lexical complexity, foreign Masters outperform Chinese Masters in lexical diversity but fall behind in lexical sophistication. Chinese-English learners seem to involve more academic and advanced but less diversified words in their academic writing; in terms of syntactic complexity, natives tend to product relatively longer mean length of T-unit and employ much more subordination (including clauses and dependent clauses) and verb phrases (including finite or non-finite verb phrases) in their academic writing, while nonnatives are inclined to output shorter mean length of T-unit and involve more coordination in their theses abstracts, which is consistent with what has been verified in previous studies. The findings of the study reveal some common features of academic writing in terms of vocabulary and sentence patterns, which further provides references for the teaching practice of academic thesis writing.