Abstract: A 270026-type Fe-Si-Al magnetic powder core with an outer diameter of 270 mm, and magnetic permeability of 26 was prepared, using insulating film-coated Fe-Si-Al magnetic powder as raw material and Zn(H₂PO₄)₂·2H₂O pretreated silica powder as filler. The effect of Zn(H₂PO₄)₂·2H₂O dosage on the magnetic properties and flexural strength of prepared Fe-Si-Al magnetic powder cores was studied. The results show that when the dosage of Zn(H₂PO₄)₂·2H₂O is 15% of the mass of silica powder, the magnetic permeability is determined to be about 24.8 in the frequency range from 1 to 1 000 kHz. Under the condition of frequency with 100 kHz and DC magnetic field with 100 Oe, the percentage of DC superposition of magnetic powder core is close to 85%. At the frequency of 200 kHz, Q value of the quality factor of magnetic powder core reaches 141. At the frequency of 50 kHz and magnetic flux density of 100 mT, the magnetic loss is lower than 175 mW/cm³. The flexural strength reaches 19.7 kPa. The prepared sample of 270026-type Fe-Si-Al powder core shows much higher magnetic properties and mechanical strength than those of the commercial 270026-type Fe-Si-Al powder core product.