This study investigates how academic disciplines impact second language (L2) lexical competencies. Prior L2 research has often overlooked the broader effects of disciplinary backgrounds on lexical development. To address this gap, this study utilized lexical decision, memory, and semantic fluency tasks to examine lexicon recognition, memory, and storage processes among L2 Chinese learners from various academic fields. The study participants comprised 16 students from the Humanities and Social Sciences (HSS) disciplines and 11 from the Science and Engineering (S&E) disciplines, all having passed HSK level 4. The tasks were conducted using E-Prime 2.0. The findings revealed distinct cognitive strategies and thinking patterns among the participants from different disciplines . These strategies and patterns affected lexical task performance in terms of accuracy and response times. Although lexical memory exhibited no significant variation among the groups, discipline-specific tendencies were observed in the formation of semantic networks. Learners from S&E disciplines preferred mastering field-relevant Chinese terminology, whereas HSS learners tended to acquire words outside their specific disciplines. This observation highlights how learners' disciplinary backgrounds influence their vocabulary acquisition and the organization of semantic networks in L2.