FeNiMo/SiO2powder cores were prepared using the sol–gel method. Tetraethyl orthosilicate (TEOS) was added to produce an amorphous SiO2coating outside the FeNiMo particles to form a core–shell structure. The thickness of the SiO2layer was designed by varying the concentration of TEOS, and the optimized permeability and magnetic loss of the powder core could achieve 78.15 and 633.44 kW m−3at 100 kHz and 100 mT, respectively. Compared with other soft magnetic composites, these FeNiMo/SiO2powder cores have a significantly higher effective permeability and a lower core loss. Surprisingly, the high-frequency stability of permeability could be substantially enhanced through the insulation coating process in whichμf/μ100 kHzcould reach 98.7% at 1 MHz. In comparison with 60μcommercial products, the comprehensive soft magnetic properties of the FeNiMo/SiO2cores were superior to most manufacturers, which would be potentially applied to high-performance inductance devices in high-frequency ranges.