NOVELTY - Nano-palladium or palladium-platinum alloy electro-catalyst is prepared by dissolving palladium salt or compound of the palladium salt and platinum salt in water, adding complexing agent solution, heating at 0-80 degrees C for 5 minutes to 8 hours, adjusting pH value to 5-12, adding carbon carrier, dropping reducing agent sodium borohydride, hydrazine or formic acid solution at 0-80 degrees C for 10 minutes to 10 hours, and carrying out heat treatment in inert atmosphere or reducing atmosphere at 100-300 degrees C for 0.5-10 hours to produce carbon-palladium or palladium-platinum electro-catalyst.    USE - Preparation of nano-palladium or palladium-platinum alloy electro-catalyst for fuel cell used for anode catalyst of direct formic acid fuel cell or cathode catalyst of direct methanol fuel cell.    ADVANTAGE - The method provides catalyst that is controllable and adjustable.    DETAILED DESCRIPTION - Preparation of nano-palladium or palladium-platinum alloy electro-catalyst comprises:    (A) forming palladium metal complex, weighing palladium salt, dissolving into water then into supersonic making the metal palladium salt completely dissolve with the complexing agent with 0.1-10 M concentration, heating at 0-80 degrees C and keeping temperature stirring, and cooling down at room temperature producing component (a);    (B) adjusting of pH of solution, injecting of carbon carrier, dropping 0.05-4% M sodium hydroxide solution which concentration is 0.05-4% mol/L to component (a), controlling pH at 7-12; adding the carbon carrier, using ultrasonic, and making the solution distribute equally to prepare component (b), where mass percent of the carbon carrier in final palladium/carbon (Pd/C) catalyst is 20-80%, material of carbon carrier is activated carbon, single-wall carbon nanotubes, multi-wall carbon nanotubes, mesoporous carbon, and/or carbon fiber;    (C) reducing a metal complex, dropping reducing agent solution into the component (b) at 0-80 degrees C, and continuously stirring to react fully, where the reducing agent is sodium borohydride, hydrazine or formic acid solution, pump filtering, washing for several times again and again until no chlorine ion is present in the washed solution, placing the catalyst in vacuum drying cabinet at 70 degrees C for 3 hours producing component (c); and    (D) heat treating the catalyst, inletting nitrogen, argon gas, hydrogen or mixed gas of them under room temperature to remove air in furnace tube, carrying heat at 100-300 degrees C for 0.5-8 hours, cooling down to room temperature under protecting of the nitrogen or the argon gas, and producing Pd/C catalyst.