Achieving synesthesia is an effective way to enhance audio-visual communication, improve interactive experience and promote information dissemination. The work aims to explore the synaesthesia metaphor method for visual design of musical style, and provide reference for realizing the effective correspondence between musical style and visual expression. The design relationship between musical style visualization and synaesthesia metaphor was analyzed from different disciplinary perspectives, and then corresponding design ideas were put forward based on this. Finally, the specific design process was discussed by combining the design cases of "metal music" and "jazz music". The relationship between visual design of musical style and synaesthesia metaphor was clarified, and four methods were proposed based on this:acquisition, construction, expansion, and evaluation. Synaesthesia metaphor can be applied to the visual design of musical style, making the transition process between music and vision clearer, allowing people to "resonate" with the design content, and providing new ideas and references for the visual design of musical style.