In this study, the effects of transverse magnetic field annealing and mixing fine powder on the soft magnetic properties of FeSiBC soft magnetic powder cores (SMPCs) are investigated. The results show that with the increase of transverse magnetic field intensity, the core loss of FeSiBC SMPCs decreases and then increases with a continuous increase in permeability compared to the zero magnetic field treatment. Wherein, the effective permeability of the powder cores is increased from 58.07 to 59.63 after transverse magnetic field annealing at a magnetic field intensity of 900 Gs and annealing temperature of 430 ℃. It shows that mixing the FeSiBC amorphous crushed powder with fine powder and transverse magnetic field annealing are effective ways to further promote amorphous SMPCs to meet the requirements of the development of electronic devices, and the prepared high-performance SMPCs also have a certain prospect of industrial application.