Clarifying how DC bias fields affect the magnetic properties of soft magnetic composites (SMCs) plays a vital role in optimizing the material design of magnetic components. In this paper, composite SMCs composed of FeSi with high DC-bias performance and FeSiAl with low loss were fabricated using the phosphating process. The microstructure and composition of insulating layers have been systematically studied. The dependence of SMC’s magnetic properties on FeSi content under different external bias fields has also been explored in detail. The results showed that the density, saturation magnetic flux density and anti-magnetization capability of FeSiAl/FeSi SMCs were gradually improved with increasing FeSi content. In addition, when the bias field exceeds 200 Oe, the sample with 80 wt% FeSi unexpectedly has the lowest core loss. The Maxwell simulation showed that SMCs with higher FeSi content, under the same external bias field, own weaker magnetization states. This indicates that the DC bias field can obviously change the magnetization state of FeSiAl/FeSi SMCs. Meanwhile, the magnetization state can determine the core loss when samples are subjected to greater DC bias excitations. This work would contribute to revealing the relationship between core loss and magnetization state, providing novel insights into the design of SMCs composition for high-power applications.