A preparation of thermal contraction sleeve is disclosed. In this method, polyethylene fibers are elongated by 850%˜1,200% and are exposed to a radiation of 2.5˜3.5 Mrads, thus being cross-linked. The first surface of a fabric sheet, made of the polyethylene fibers, is exposed to a voltage of 20,000˜25,000 V while passing over a plurality of rollers, thus being modified at the first surface. A first matrix sheet, melt-extruded at a temperature of 300° C.˜380° C., is formed on the modified first surface of the fabric sheet, prior to an integration of the first matrix sheet with the modified surface of the fabric sheet. The integration is accomplished by a first elastic roller and a first cooling roller. The second surface of the fabric sheet is processed in the same manner as that described above. A second matrix sheet is layered on the modified second surface of the fabric sheet, thus forming a fabric-matrix layered body. The matrix sheets of the fabric-matrix layered body are exposed to a radiation of 2.5˜3.5 Mrads, thus being cross-linked.