Abstract: The Fe_75.9Cu₁Si₁₃B₈Nb_1.5Mo_0.5Dy_0.1 alloy iron core is designed on the basis of the Finemet alloy FeSiNbBCu series to study the soft magnetic properties of the core. The results show that the commercial amorphous alloy ribbons Fe_75.9Cu₁Si₁₃B₈Nb_1.5Mo_0.5Dy_0.1 has complete amorphous structure in as-cast state and the α-Fe nanocrystalline phase precipitates on the amorphous matrix after vacuum annealing. The Fe_75.9Cu₁Si₁₃B₈Nb_1.5Mo_0.5Dy_0.1 alloy has high ΔT_x value(192 K) and good thermal stability, which can better control the formation of nanocrystalline structure. The transverse magnetic field annealing can greatly increase the μ_e of the material and reduce the P_s, which is more significant for the ribbons. The optimum annealing process of the Fe_75.9Cu₁Si₁₃B₈Nb_1.5Mo_0.5Dy_0.1 alloy is that the transverse magnetic field of 0.10 T is applied and the temperature is kept at 833 K for 30 min. And the best saturation magnetic induction (B_s) is 1.39 T, for H_c is 4.6 A/m, μ_e=2.5×10⁴ (1 kHz) and 1.52×10⁴ (100 kHz). This material has potential application value considering the tendency of electronic component manufacture towards high frequency and miniaturization.