Abstract: The alloy composition design was performed by element substitution method. Six kinds of nanocrystalline alloys were prepared by single roll rapid quenching and amorphous crystallization methods. The glass forming ability, thermal stability and crystallization process of amorphous soft magnetic alloys were characterized by X-ray diffraction（XRD） and differential scanning calorimetry（DSC）. The quenched magnetic cores were treated by ordinary heat treatment and transverse magnetic field heat treatment. The soft magnetic DC tester（MATS-2010SD） and soft magnetic AC tester（MATS-2010SA）were used to test the core after heat treatment. The experimental results show that the initial permeability of Fe₆₄Ni₁₂Si₁₃B₈Nb₂Cu₁ alloy is 3.247 k, the coercivity is 4.217 A/m, and the loss is 27.14 W/kg at 0.2 T/100 kHz. The soft magnetic alloy with low permeability, low coercivity and low loss is obtained.