The present study delves into the application of ETcad technology in down jacket pattern making and conducts a comparative analysis with traditional manual pattern making. Through the analysis of practical cases, the study reveals the significant advantages of CAD technology in improving pattern making efficiency, reducing production costs, and enhancing product quality. The research findings indicate that ETcad technology, by means of accurately calculating down filling quantities, optimizing pattern design, and automating material layout, has dramatically shortened the pattern making time, reduced material waste, and increased fabric utilization. Moreover, it has demonstrated remarkable performance in handling complex designs and rapidly responding to market demands, thereby enhancing the market competitiveness of enterprises. This study also explores the impact of CAD technology on traditional pattern making processes and its future development directions, providing theoretical support and practical references for the digital transformation of the clothing industry.