The invention discloses corrosion-resisting steel. The corrosion-resisting steel comprises, by mass percent, 3.6%-4.2% of carbon, 3.2%-3.8% of magnesium, 1.8%-2.2% of silicon, 0.24%-0.34% of copper, 0.8%-1.2% of molybdenum, 0.3%-0.5% of nickel, 1%-3% of cobalt, 0.5%-1% of vanadium, 0.2%-0.4% of manganese, 1.2%-2% of niobium and the balance iron. According to the corrosion-resisting steel, carbon,magnesium, silicon, copper, molybdenum, nickel, cobalt, vanadium, manganese and niobium are adopted as raw materials, reasonable matching is carried out, the components achieve interaction and mutualeffects, and it is guaranteed that the prepared steel has good corrosion resistance.