Abstract: FeSiBCrC amorphous alloy powders with different particle sizes were prepared by a new industrial gas-water atomization, and the effects of particle size and annealing temperature on the properties of the FeSiBCrC amorphous magnetic cores were investigated in this paper. The results show that the FeSiBCrC alloy powders with the median particle size (D₅₀) ≤25 μm are all amorphous, and the width of the supercooled liquid phase region (ΔT) can reach 40 ℃, indicating the strong amorphous formation ability of the FeSiBCrC alloy powders. The saturation magnetization (M_s) and coercivity (H_c) of the amorphous powders increase with the increase of particle size. D₅₀=5 μm, M_s=144.6 emu∙g^‒1, and H_c=1.8 Oe; however, D₅₀=30 μm, M_s=152.6 emu∙g^‒1, and H_c=9.8 Oe. The permeability (μ_e) of the amorphous magnetic cores with different particle sizes has the good stability in the frequency range of 0.1~600.0 kHz, and the permeability of fine powders show better than that of the coarse powders. The magnetic loss (P_c) of all amorphous magnetic cores increases with the increase of frequency. The finer the particle size, the more obvious the effect of annealing on reducing the magnetic loss, which is decreased by about 84% at D₅₀=5 μm, while is only decreased by about 30% at D₅₀=30 μm. After annealing at 500 ℃, the magnetic loss of amorphous magnetic cores at D₅₀=5 μm reaches the minimum as 578 mW∙cm^‒3.