The rapid development of computer multimedia technology has brought change opportunities and new challenges for high school music education. This paper is based on the “general high school music curriculum standards (2017 version of the 2020 revision)” in the “music composition” module requirements, combined with the content of the human voice version of the “music composition” textbook, analyzes the potential for the application of computer multimedia technology in high school music composition teaching, describes the current teaching faced by the limited effect of hierarchical teaching, the students’ practice ability is weak, the textbook is not synchronized with the technological update and other issues. The study takes 39 students from National High School in Taian City, Shandong Province as the object, and puts forward targeted strategies through teaching practice: building a multimedia teaching platform, implementing personalized teaching; introducing project-based creative practice, strengthening process evaluation; integrating multi-source materials, and dynamically updating teaching content. The study shows that the reasonable application of computer multimedia technology can effectively enhance students’ interest and ability in music composition and provide reference for the reform of high school music composition teaching.