Computer-aided design (CAD) and multimedia technology, as important tools of digital design, are widely used in the field of fashion design. In this article, the author discusses the synergy between computer-aided design and multimedia technology in improving the efficiency of fashion design resources and cultural expression. Mathematical modeling, quantitative evaluation, and case analysis indicated that the integration of the two technologies not only optimizes the design process and improves the utilization rate of materials but also realizes the digital extraction, redesign, and modern expression of cultural elements. The author puts forward a set of comprehensive frameworks that integrate concepts of green design and technical reality and provides theoretical support and practical reference for the sustainable development and cultural innovation of fashion design.