The invention discloses an ultralow-temperature high-toughness special nodular cast iron metal material and a preparation method thereof. The ultralow-temperature high-toughness special nodular cast iron metal material comprises the following raw materials in parts by weight: 92-95 parts of pig iron, 5-8 parts of scrap steel, 1-2 parts of silicon iron, 2-3 parts of ferromanganese, 0.5-1 part of bismuth iron, 1.6-1.8 parts of a nodulizing agent and 0.5-0.8 part of an inoculant. The ultralow-temperature high-toughness special nodular cast iron metal material is prepared by smelting the pig iron, the scrap steel, the silicon iron, the ferromanganese, the bismuth iron and the inoculant in an electric furnace, performing metamorphic inoculation before furnace, casting forming and cooling. The ultralow-temperature high-toughness special nodular cast iron metal material has good structural performance, casting forming performance and machinability, can be applicable to workplaces with high requirements on high toughness, high strength, high wear resistance, cold resistance, corrosion resistance, shock absorption and safety performance, can be applied to high-speed trains, a wind power industry, vehicles, petroleum, a petrochemical industry and other industries, has relatively cheap raw materials, and has a very high practical value, a very high promotional significance and a wide market prospect.