NOVELTY - Preparing nickel nanoparticle catalyst, comprises: (a) dispersing pre-treated multi walled carbon nanotube in mixed acid solution, condensing and refluxing, acidifying, drying to obtain acidified multi walled carbon nanotube, dispersing in sensitizer mixed solution, filtering and drying to obtain sensitized multi walled carbon nanotube, dispersing in mixed solution, washing, drying to obtain activated multi-walled carbon nanotube, and (b) dispersing in water, adding nickel chloride hexahydrate and complexing agent, ultrasonically dispersing, adding hydrazine hydrate, filtering and drying.    USE - The catalyst is useful in ethanol fuel cells.    ADVANTAGE - The catalyst has excellent catalytic activity for ethanol.    DETAILED DESCRIPTION - Preparing nickel nanoparticle catalyst, comprises: (a) pre-treating multi walled carbon nanotube and dispersing in a mixed acid solution containing 120 ml of concentrated nitric acid and concentrated sulfuric acid, condensing and refluxing, then acidifying multi walled carbon nanotube to pH of 7, drying under vacuum condition to obtain acidified multi walled carbon nanotube, dispersing the acidified multi walled carbon nanotube in 30-50 ml mixed solution of sensitizer for 30 minutes, filtering, thoroughly cleaning and drying under vacuum condition to obtain sensitized multi walled carbon nanotube, where the mixed solution comprises stannous chloride (8' 10--3 mol), hydrochloric acid (3' 10-3 mol) and poly(decyl methacrylate) (0.01-0.03 g), ultrasonically dispersing the sensitized multi walled carbon nanotube in 30-60 ml mixed solution at 30 degrees C, washing, drying under vacuum condition to obtain activated multi-walled carbon nanotube, where the mixed solution comprises palladium chloride (1' 10-3 mol), hydrochloric acid (1' 10-3) and poly(decyl methacrylate) (0.01-0.03 g), and (b) dispersing multi walled carbon nanotube in 40-80 ml water, then adding nickel chloride hexahydrate and complexing agent to form mixed solution, ultrasonically dispersing the mixed solution for 30 minutes, regulating pH to 9-11 by 1mol/l alkali, then adding hydrazine hydrate, controlling the reaction temperature to 40-90 degrees C for 40-60 minutes, filtering, drying under vacuum condition to obtain nickel nanoparticles load multi walled carbon nanotube catalyst.