This study makes both qualitative and quantitative analyses on modal sequences in 60 RA introductions selected from four journals in the field of applied linguistics.The introductions are also marked with moves and steps according to Swales' CARS model so that the distribution of modal sequences and their discourse function in each move and step can be further analyzed.The major findings of the study are listed as follows.Modal sequences are most frequently used in the move-steps of "literature review" and "research findings".In the part of literature review,the use of modal verbs helps to demonstrate the authors' understanding,learning and critical thinking about their research field,indicating the necessity and significance of the current research.In the part of research findings,it is found that a group of verbs and adverbs with positive meaning is used after the modal verbs to highlight the significance of research results.Besides,it is found that the authors tend to avoid human subjects before modal verbs to keep the article objective and trustworthy.