Chemical fiber felt is often subjected to various external forces such as stretching, curling and twisting in the process of processing, so that the fiber changes its original shape. The wool wool has good elasticity, it tries to revert to its original form, resulting in a variety of stress in the fiber, the internal stress in quite a long period of time gradually decreases until the elimination of it, often to the processing of wool products is difficult, this is also one of the factors of wool product size in processing and use in the process and form is not stable. The plasticity of wool means that the wool can be rapidly attenuated under the condition of hot and humid conditions. It can change the existing form according to the external force, and then cool or dry to keep the shape down. The main stop of wool fiber is the cortical layer composed of cortical cells. High sulfur and low sulphur containing two kinds of wool protein in cortical cells, the former is the main component of the matrix, its molecular chain was amorphous curling; the latter has a spiral structure of molecular chain, in cortical cells composed of basic raw fiber (protofibril). The primary fibril then forms the fibril, and the fibril is further composed of fibrils. All kinds of raw fiber are buried in the tomb, and the original fiber and the discriminator can be connected by two sulfur bonds. Some research data indicate that: 0 the fibril in cortical cells is about 0.25m in diameter, and the diameter of fibrils is 7. 5nm (75A), and the diameter of basic fibril is about 2nm.