High molecular magnetic materials is one of the materials of the the human while constantly open up new application areas of the magnetic polymer (synthetic resin, rubber), SMD ferrite core given the magnetic polymer traditional application to a new meaning and content. The early magnetic material derived from natural magnet, only after use of a magnetite sintered or cast into a magnetic material (ferrite), now commonly used industrial magnetic material has three, i.e., ferrite magnets, rare earth magnets, and alnico magnet and so on. Their disadvantage is both hard and brittle, poor workability. In order to overcome these drawbacks, the magnetic powder is kneaded in a plastic or rubber made of polymer magnetic material was born. Such a polymer made of composite magnetic materials, light weight, easy to be processed into high dimensional accuracy and the complex shape of the products, but also with other elements, forming one and so on, more and magnetic bead core more attention. Polymer magnetic materials can be divided into two categories, namely, structural and composite. The so-called structure-type means does not add an inorganic magnetic powder while the polymer prepared in the magnetic body. Practical value composite.