The invention provides a raw material used for preparing carbon steel, its preparation method, and the carbon steel. The raw material comprises 55-65% of Fe2O3, 15-25% of Al, 0-0.3% of graphite, 0-0.2% of Si, and the balance Fe. The method comprises the following steps: weighing reactants, dry-grinding the reactants, putting the mixed reaction material in a mold, compacting at 30-70MPa with a press, putting a detonator in the upper part of the reaction material, putting the detonator and the reaction material in a reaction device, blowing a reaction container with argon at room temperature to eliminate air in the container, heating the container to 200DEG C, blowing again to remove the air, letting 4-7MPa of argon in the container, continuously heating the container, allowing a reaction of the detonator to start when the temperature in the container reaches about 250DEG C, completing the reaction in seconds, and cooling the generated products to room temperature with a furnace under the protection of argon to obtain ferrite with the material microstructure being nanometer crystal and pearlite with the material microstructure being in a micrometer zone.