Abstract: Iron-based amorphous alloys exhibit many desirable features, such as low coercivity, high permeability, high electrical resistivity, low loss, and good frequency characteristics, which make them a kind of viable energy-saving and environmentally-friendly materials. Their attractive features are due to their isotropic property, small structural correlation dimension, and magnetic anisotropic constant. The interactive coupling between the α-iron (Fe) nanocrystalline phase and amorphous soft magnetic phase further reduces the magnetic anisotropy and magnetostrictive effect of the Fe-based amorphous and nanocrystalline composites. Therefore, Fe-based amorphous and nanocrystalline alloys have a high saturation flux density and high magnetic permeability, and have been widely applied for electric power, electronics, and information transmission and conversion industries. Now, Fe-based amorphous and nanocrystalline alloys have been produced and applied to various areas on a large scale. In this paper, the development histories, situation, and tendency of Fe-based amorphous and nanocrystalline alloyswere briefly summarized. The research results of Fe-based bulk and ribbon amorphous alloys, along with nanocrystalline alloys with high saturation flux density (B_s), were reviewed in detail. The main contents of this paper include the compositions and properties of high-B_s Fe-based bulk and ribbon amorphous alloys; the compositions, structure and properties of high-B_s Fe-based nanocrystalline alloys; and the effects of alloying elements on the magnetic properties. These results will provide valuable insights that can be used for the development of Fe-based soft magnetic materials with a high saturation flux density.