NOVELTY - Preparing fuel cell composite catalyst involves absorbing transition metal ion and dopamine with 0.1-2 milligrams per milliliter platinum on carbon catalyst in mass ratio of 1:0.7:1 and then mixing the absorbed material with mixed solution of ethanol and water as solvent. The mixed material is subjected to perform ultrasonic treatment for 10-60 minutes and then the treated material is stirred with tris-hydrochloride buffer liquid and dopamine in mass ratio of 1:1-1:3. The stirred material is polymerized at 0-30 degrees C for 2-24 hours and then the polymerized material is washed with deionized water.    USE - Method for preparing fuel cell composite catalyst (claimed) used in proton exchange membrane for fuel cell and electrolyte. .    ADVANTAGE - The method enables to prepare fuel cell composite catalyst in simple manner, with high activity, large specific surface area, and has solved catalyst migration and agglomeration problem in burning process and controlled particle size effectively.    DETAILED DESCRIPTION - Preparing fuel cell composite catalyst involves absorbing transition metal ion and dopamine with 0.1-2 milligrams per milliliter platinum on carbon catalyst in mass ratio of 1:0.7:1 and then mixing the absorbed material with mixed solution of ethanol and water as solvent. The mixed material is subjected to perform ultrasonic treatment for 10-60 minutes and then the treated material is stirred with tris-hydrochloride buffer liquid and dopamine in mass ratio of 1:1-1:3. The stirred material is polymerized at 0-30 degrees C for 2-24 hours and then the polymerized material is washed with deionized water. The washed material is centrifuged and then the centrifuged material is added with transition metal precursor and platinum in molar ratio of 1:1-1:5. The obtained material is stirred for 2-24 hours and then the stirred material is added with tetraethyl orthosilicate at pH 1-6. The obtained material is stirred for 10-30 minutes and then the stirred material is hydrolyzed under acidic conditions to form silicon dioxide. The obtained material is dried to obtain nitrogen-doped carbon-modified platinum-based alloy catalyst and then the obtained catalyst is kept in a tubular furnace at 600-1000 degrees C under nitrogen or argon gas protective atmosphere for 0.5-3 hours. The heated material is cooled and added with polytetrafluoroethylene and then the obtained material is mixed with distilled water and hydrofluoric acid in 1:0.7-1:3. The mixed material is stirred for 8-24 hours and then the stirred material is centrifuged, washed, dried and ground to obtain the desired product.