Surface-cracked skin-core composite fiber and preparation method thereof

The invention relates to a surface-cracked skin-core composite fiber and a preparation method thereof. The surface-cracked skin-core composite fiber is composed of a skin layer and a core layer, wherein the surface of the surface-cracked skin-core composite fiber has axial cracks, the skin layer is made of polyester with a high crystallization rate, and the core layer is made of polyester with a low crystallization rate. Since there is a difference value between the crystallization rates of the skin layer material and the core layer material, cooling crystallization conditions of the skin layer and the core layer are different when a fiber is jetted from a spinneret plate, cooled and drawn, the skin layer rapidly finishes crystallization while the core layer is slow in crystallization, and the skin layer easily produces axial cracks during drawing; and ordered control is carried out, so the surface-cracked skin-core composite fiber is obtained.