Soft magnetic functional composite material is a composite material composed of soft magnetic ferrite and polymer matrix, which has soft magnetic function. For soft magnetic materials, low Coercivity and high permeability are required to minimize the effect of permeability falling rapidly with the increase of frequency. It is advantageous to use thin film materials with high resistivity and small thickness. Soft magnetic functional composites can just play these characteristics. This is because the polymer matrix is insulating, and the composite with conductive magnetic body improves the resistivity. At the same time, the polymer is easy to process into thin sheets with good strength and flexibility. More importantly, the polymer separates and encloses the magnetic body, thus greatly reducing the eddy current loss and not heating the magnetic material. The loss of the magnetic iron core used as a low-frequency device is only 1C} W} kg. This type of material is mainly used for the iron core of low frequency (or power frequency) small and medium-sized transformers, with the characteristics of high efficiency and low consumption.