Research article introductions (RAIs) have been attracting much attention in the field of genre analysis due to their complicated discourse structure and linguistic features. This study follows Biber’s multidimensional analysis to compare the dimensional and linguistic features of 320 RAIs of four disciplines: linguistics, mechanical engineering, philosophy and physics in the PLOS ONE database. The results show that RAIs of different disciplines display some similarities, such as the relatively lower degree of overt persuasion, clear and independent in-text references, and more abstract language style. However, there are significant differences in linguistic features such as third-person pronouns, private verbs, the passive voice, and nominalization, which correspond to the disciplinary grouping. The study confirms the fact that the disciplinary characteristics reflected by different types of disciplinary practice of knowledge exploration, construction and dissemination shape the linguistic features of academic discourse.