Abstract: The present work is devoted to the development of Fe-(B-Si)-Zr amorphous alloys with high glass-forming ability and good magnetic properties. Using the cluster-plus-glue-atom model proposed for ideal amorphous structures, FeFe₁₁B₃Si(Fe_1−xZr_x) was determined as the cluster formula of Fe-(B-Si)-Zr alloys. The glass formation and thermal stability of the serial alloys, namely, FeFe₁₁B₃Si(Fe_1−xZr_x) (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.75, and 1.0), were studied by the combination of copper mold casting, X-ray diffraction, and differential thermal analysis techniques. The maxima of glass-forming ability and thermal stability were found to occur at the compositions of FeFe₁₁B₃Si(Fe_0.6Zr_0.4) and FeFe₁₁B₃Si(Fe_0.5Zr_0.5). The alloys can be cast into amorphous rods with 1.5 mm diameter, and upon reheating, the amorphous alloys exhibit a large undercooled liquid span of 37 K. The saturation magnetization of the FeFe₁₁B₃Si(Fe_0.5Zr_0.5) amorphous alloy was measured to be 1.4 T.