The invention relates to a preparation method of an ultramicroporous high-specific-area denitrification catalyst material, belonging to the field of inorganic catalyst flue gas denitrification. The preparation method is characterized in that the pore size of the catalyst is 1-2nm, the high specific area is 550-600 m<2>/g, copper oxide is used as an active component, and the molecular proportion of the copper oxide is not lower than 5%. The synthesis method comprises the following steps: dissolving nonionic surfactant, organic carboxylic acid, inorganic acid and copper salt in an ethanol solution containing deionized water according to the proportion of the synthetic material, and meanwhile, adding an aluminum source while stirring; and after continuing stirring for some time, carrying out heat treatment solvent volatilization and high-temperature roasting on the reactants to prepare the high-specific-area denitrification catalyst. The preparation technique is simple and feasible, low in cost and easy for industrial amplification, and has environment-friendly effect. The methane (CH4) used as the reducer has high denitrification activity within the temperature range from 400 to 600 DEG C; and when the reaction temperature is higher than 600 DEG C, and the conversion rate of NO is up to 100%.