NOVELTY - A fuel cell catalytic agent comprises a supporter that is conductive ceramic cladded with a nanofilm layer on the surface. The thickness of the carbon nanofilm is 0.2-8 nm.    USE - A fuel cell catalytic agent.    ADVANTAGE - The fuel cell catalytic agent adopts carbon cladding conductive ceramic as a supporter in comparison with carbon supporter catalytic agent, and has high chemical and electrochemical stabilities. The supporter has higher conductive performance in comparison with common ceramic supporter and the thickness of a carbon film layer is controllable and has no effect to the ceramic. The catalytic agent has high electrochemical active area in comparison with common ceramic catalytic agent. It has better electricity output performance and cell stability.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for preparing a fuel cell catalytic agent, comprising putting a conductive ceramic in absolute ethyl alcohol for dispersing ultrasonically, dripping the solution on the substrate to form a film on the surface, putting the film sample in the Kaufman gas ion source, leading hydrocarbon gas, keeping the pressure at 2-7x 10-1, irradiating the sample for 0.5-4 hours by an electronic beam at 80 v and current density of 60 mu ampere/cm2; and keeping the sample at 400-800 degrees C and preparing the carbon cladding conductive ceramic supporter. The catalytic agent precursor salt is dissolved into the deionized water or alcohol or alcohol aqueous solution, and agitated in the presence of nitrogen. The pH of the solution is kept at 9-13. The solution is heated for 2-5 hours at 130-160 degrees C, thus preparing the stable metal catalytic agent. The agent is added to the conductive ceramic supporter with the carbon nano film layer, and agitated for 8-10 hours. The hydrocarbon air source is methane, ethane, propane, butane, ethyne, allylene, ethane, propylene, or butane. The weight ratio of alcohol in alcohol aqueous solution and the water is 0.5-100:1. The alcohol is methyl alcohol, alcohol, propyl alcohol, or isopropyl alcohol. The catalytic agent precursor salt is hexachloroplatinic acid, ruthenium chloride, palladium chloride, iridium chloride, and/or cobalt nitrate.