Under the guidance of core competencies, The Routine Revision of English Curriculum Standards for General Senior High Schools (2017 Edition, 2025 Revision) has introduced systematic adjustments and structural optimization to the senior high school English word list, reflecting the educational value in curriculum philosophy. This paper first outlines the major changes in the vocabulary revision, noting an increased emphasis on articulation between school stages, theme-based instruction, and register differentiation. On this basis, it analyzes the reconstruction of vocabulary functions from the perspective of core competencies and clarifies how vocabulary selection embodies language ability, cultural awareness, thinking capacity, and learning ability. Next, it draws on usage-based second language acquisition theory, construction grammar, and mechanisms of entrenchment to explain the cognitive rationale of the vocabulary revision, demonstrating that it aligns with the processes of forming, organizing, and consolidating language knowledge through authentic use. Finally, within the framework of the activity-based approach to English learning, the paper develops an implementation pathway for teaching English vocabulary in senior high schools, integrating vocabulary learning into classroom practice through activities of learning and understanding, application and practice, and transfer and innovation. This paper aims to provide theoretical support and practical guidance for high school English vocabulary instruction, thereby promoting the all-round development of students’ core competencies.