TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: Diameter of the platinum alloy catalyst is 2-4nm. The ratio of transition metal and platinum in the platinum alloy catalyst is 1:1.5-2, and the total alloy content of platinum alloy catalyst is 15-25 wt.%. The transition metal precursor is a compound comprising palladium, ruthenium, cobalt, nickel, iron, chrome, copper, tin, iridium, molybdenum, tungsten or titanium, preferably palladium chloride and/or ammonium hexachloropalladate. Preferred Method: The mixing ratio of transition metal precursor and the first solvent is 0.01-10 mg/ml. The heating step comprise stirring and heating at 80-170 degrees C for 150-270 minutes. The mixing ratio of the platinum precursor and the second solvent is 0.01-10 mg/ml.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The first solvent and the second solvent are water, urea, ethylene glycol, diethylene glycol and/or triethyleneglycol. The carbon based catalyst carrier is activated charcoal, carbon black, graphene and/or carbon nanotube. The reducing agent is sodium borohydride, hydrazine, sodium hydroxide or formaldehyde. EXAMPLE - 22 mg Palladium chloride was added into ethylene glycol (100ml) and stirred for 24hours and palladium precursor solution was obtained. 100 mg Super-P (RTM Conductive carbon black) was dispersed in 100 ml ethylene glycol and added to the obtained palladium precursor solution and a mixed solution was obtained. The mixed solution was ultrasonically treated for 15 minutes and then titrated with 1 M sodium hydroxide and the pH was adjusted to 12. Then the mixed solution was stirred for 4 hours at 400 revolutions/minute at 170 degrees C and cooled to room temperature. 18 mg Chloroplatinic acid was dissolved in 100 ml ethylene glycol and titrated with 1 M sodium hydroxide solution and the pH was adjusted to 10. The above prepared solutions were mixed and stirred for 4 hours at 400 revolutions/minute at 170 degrees C and then cooled to room temperature and dried at 100 degrees C for 10 hours to obtain the platinum alloy catalyst.