NOVELTY - A chromium carbide modified iron-based metal double-pole plate comprises substrate which is an iron alloy metal plate and chromium carbide diffusion layer. Iron alloy metal plate has thickness of 0.1-3 mm. The alloy chemical component comprises (wt.%): carbon (C, less than or equal to 0.50), silicon (Si, 0.17-0.37), manganese (Mn, 0.35-0.80), chromium (Cr, less than or equal to 0.25), nickel (Ni, less than or equal to 0.30), copper (Cu, less than or equal to 0.25), phosphorus (P, less than or equal to 0.35) and sulfur (S, less than or equal to 0.04). Diffusion layer has thickness of 1-30 mu m, where corrosion speed is less than 10 A/cm2 and pressure is 150-200 N/cm2.    USE - Chromium carbide modified iron-based metal double-pole plate for fuel cell.    ADVANTAGE - The plate does not affect the battery performance, thus improving corrosion resistance and high conductivity.    DETAILED DESCRIPTION - Chromium carbide modified iron-based metal double-pole plate comprises substrate which is an iron alloy metal plate and chromium carbide diffusion layer. Iron alloy metal plate has thickness of 0.1-3 mm. The alloy chemical component comprises (wt.%): carbon (C, less than or equal to 0.50), silicon (Si, 0.17-0.37), manganese (Mn, 0.35-0.80), chromium (Cr, less than or equal to 0.25), nickel (Ni, less than or equal to 0.30), copper (Cu, less than or equal to 0.25), phosphorus (P, less than or equal to 0.35) and sulfur (S, less than or equal to 0.04). Diffusion layer has thickness of 1-30 mu m. Corrosion speed is less than 10 A/cm2, where pressure is 150-200 N/cm2, contact resistance is 10-20 ohm cm2 and chromium carbide is Cr3C2, Cr7C3 and/or Cr23C6. An INDEPENDENT CLAIM is included for preparation of the metal bipolar plate which comprises modifying steps. The first modifying step comprises putting carbon in furnace at 800-1000 degrees C, performing heat preservation at stage glow voltage of 100-800 V, where current density is 0.5-20 mA/cm2 and vacuum degree of 50-1330 Pa; and carburizing for is 2-8 hours, where reaction gas is methane or acetylene or thiophane. The second modifying step comprises thermal reaction deposition and diffusion at 500-1000oC for 0.5-48 hours, and diffusing chromium from chromium-iron powder.