Bi-Component fiber is one kind of multi-component fiber, on the cross section of fiber exists two or more than two no mix polymer fiber. According to the types of cross section, they are side-by-side composite fiber, sheath core, and sea-island composite fiber. The composite fiber is mainly used in PU leather、yarn、wool fabric、silk textile、medical and sanitary fields. Nowadays, due to the requirement of environment protection, the genuine leather is slowly replaced by PU leather.