Synesthesia is a psychological phenomenon generated by kinds of feelings which have an effect with each other. This paper introduces the production classification and understanding of synesthesia. At the same time, the paper analyze the application of synesthesia in streamline formstyle design , iMac computer design, and our daily life. There are full of all kinds of screen in today's digital age, leading to the extinction of sense of products’ dimension. The paper brings up to build the “five senses”: taste, smell, touch, hearing, visual to rethink the way of design concepts.