TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation: The bipolar plate for fuel cell is prepared by depositing carbon chromium film in the surface of bipolar plate substrate by arc ion deposition, comprising following technological processes of placing thin plate substrate of stainless steel bipolar plate in vacuum chamber of arc ion plating after washing by ultrasonic and drying, vacuum system pumping of vacuum to 5x 10-3 Pa, charging the working gas, starting cathode target arc and adding bias pressing, performing passive film removing treatment of substrate, decreasing bias pressing at negative 300V to negative 500V, adjusting working gas to 0.2-0.8 Pa, adjusting the arc current and processing film deposition for 20-120 minutes, taking out the film coated bipolar plate after furnace cooling completely and letting vacuum go, where passive film removing treatment of substrate is performed by adopting ion sputtering method, and performing adjusting arc current of film deposition process by adopting the method adjusting arc current matching of carbon target and pure chromium target, where the proportion of carbon target arc current and chromium target arc current is 1A/3A-2A/1A. Preferred Components: The carbon chromium film is carbon chromium film single-layer film with even composition. Preferably, the carbon chromium film is carbon chromium ladder film. Alternatively, the carbon chromium film is multi-layer film. The ion sputtering ion is from glow discharge plasma of inert gas. The charged work gas is inert gas argon. Preferably, the ion sputtering ion is from arc discharge plasma evaporated by metal target material arc. The started cathode arc is metal target arc of pure chromium. Alternatively, the ion sputtering ion is from glow discharge plasma of inert gas and arc discharge plasma of evaporated by metal target material arc. Preferred Composition: The percentage content of relative ion of carbon is 10-90%. Preferably, the percentage content of relative ion of carbon changes in 10-90% following the increasing of film width. Alternatively, the percentage content of relative ion of carbon changes alternately is from 10-50% to 50-90% following the increasing of film width. The alternative cycle is 10-200 nanometers. Preferred Parameters: The arc current is 0-80A. The applied bias is negative 500V to negative 1500V. The carbon target arc current is 35-120A from beginning to finishing. Chromium target arc current is 60-150A. Preferred Conditions: The pressure of ion sputtering ion is 0.3-5 Pa. Preferred Process: Adjusting arc current is performed by adopting the arc current variety method following plating film time.