Bionic down is a kind of non biological filling "core" material, which not only has the natural characteristics of down and silk (fluffy and warm, soft and silky), but also can overcome its unavoidable disadvantages (easy to drill down, easy to pile up, easy to dust, allergic or peculiar smell). It is different from all traditional short fiber (biological and non biological) filling materials. It is developed in Japan, and the world's first long down series and medium down series Empty yarn (≥ 32%) pile structure, with excellent flexibility, not easy to break, safe and healthy, environment-friendly and other scientific and technological quality.