NOVELTY - Preparing fuel cell catalyst comprises (i) preparing polyaniline modified platinum/carbon catalyst by adding aniline monomer into aqueous sulfuric acid solution, ultrasonically stirring, adding platinum/carbon catalyst, stirring, dissolving platinum/carbon catalyst in ammonium persulfate into aqueous sulfuric acid solution, dripping iron precursor and cobalt precursor into mixed solution of platinum/carbon catalyst and aniline, stirring, reacting, drying, and grinding; and (ii) preparing nitrogen-doped carbon layer modified platinum/carbon catalyst by e.g. heating resulting catalyst.    USE - The method is useful for preparing highly efficient and stable fuel cell catalyst (claimed).    ADVANTAGE - The fuel cell catalyst: is highly efficient and stable (claimed); has good and stable oxygen reduction activity.    DETAILED DESCRIPTION - Preparing fuel cell catalyst comprises (i) weighing platinum/carbon catalyst and aniline according to mass ratio of 1:0.7-1.5, taking aniline, iron precursor, cobalt precursor and ammonium sulfate according to mass ratio of 1:2-6:0.5-1:1-4, weighing iron precursor, cobalt precursor and ammonium sulfate, adding 0.01-2 mol/l aniline monomer into aqueous sulfuric acid solution, ultrasonically stirring for 10-30 minutes, adding platinum/carbon catalyst, continuously ultrasonically stirring for 5-28 hours, taking uniformly dispersed platinum/carbon catalyst, stirring at 0-15 degrees C, dissolving in 0.01-2 mol/l ammonium persulfate into aqueous sulfuric acid solution, dripping iron precursor and cobalt precursor into the mixed solution of platinum/carbon catalyst and aniline, where the dripping time is controlled to 5-60 minutes, stirring at 0-15 degrees C, continuously reacting for 10-48 hours, drying the product, and grinding to obtain polyaniline modified platinum/carbon catalyst; and (ii) placing the platinum/carbon catalyst in a tubular furnace, heating the tubular furnace to 600-1000 degrees C under the protection of inert gas, controlling the flow speed of the inert gas is 50-500 ml/minute, maintaining the temperature at 600-1000 degrees C for 0.5-2 hours, cooling the product, adding 0.01-2 mol/l product in aqueous sulfuric acid solution, stirring at 60-90 degrees C for 2-8 hours, centrifugally washing the product, drying, and grinding to obtain nitrogen-doped carbon layer modified platinum/carbon catalyst.