Abstract: The high silicon steel soft magnetic composite cores (Fe-6.5%Si/SiO₂ by mass) were successfully prepared by fluidized in-situ chemical vapor deposition combined with the following spark plasma sintering process. The dependence of microstructures on the electrical and magnetic properties of Fe-6.5%Si/SiO₂ composite cores was investigated. The results indicate that, most of the conductive Fe-6.5%Si particles are firstly coated with SiO₂ in chemical vapor deposition, and then the highly compact and insulated Fe-6.5%Si/SiO₂ composite cores are quickly obtained in the next spark plasma sintering. The as-prepared Fe-6.5%Si/SiO₂ composite cores display the excellent electromagnetic properties as the saturation magnetization of 175 emu·g^-1, the coercivity of 15 Oe, the relative permeability of 350 at 80 kHz, the electrical resistivity of 8.6×10^-5?·m, and the core loss of 11.8 W·kg^-1 at the magnetic field of 0.2 T and 5 kHz.