Abstract: An austenitic high silicon iron-base alloy with Ni or Mn was devised based on the study on the mechanical properties and microstructure of a general high silicon iron-base alloy. The new austenitic high silicon iron-base alloy with Ni or Mn was designed by means of austenitic stainless steel and the three-element phase graph of Fe-Ni-Si or Fe-Mn-Si. The microstructure, mechanical properties and corrosion resistance of the alloy were investigated by optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), test equipment of mechanical properties, and test instrument of corrosion. The results show that the base structure of a general high silicon iron-base alloy is high silicon ferrite, which is mainly the long-range ordered Fe₃Si. Fe₃Si has low-temperature brittleness and is the main reason for silicon brittleness. The addition of 18% Ni produces austenite and causes an impact toughness up to 5.52 J·cm^-2, which is 7 times higher than a general high silicon iron-base alloy, while the corrosion resistance is equivalent with a general high silicon iron-base alloy.