The invention discloses a method for preparing 1,2-dione by catalytically oxidizing an alkyne, which is characterized in that the alkyne R1-C equivalent to C-R2 is selected as the reactant; one of palladium chloride, palladium acetate, palladium bromide, palladium trifluoroacetate and palladium trifluoromethane sulfonate is used as the catalyst; copper is selected as the co-catalyst; a mixture solution consisting ether and water is used as the solvent; and the reaction is carried out at 40 to 100 DEG C for 12 to 36 h to prepare the 1,2-dione. The catalytic oxidization reaction has a quite mild reaction condition, and has wide range of suitable substrates, high yield, simple operation of the reaction process, and convenient post-treatment. Oxygen is used as the oxidant, which is friendly to the environment and lower in cost.