The invention relates to a method for preparing lactone by means of catalytically oxidizing dihydric alcohol by the aid of heterogeneous supported metal-metal oxide catalysts under mild conditions. The method includes carrying out heterogeneous catalytic oxidation reaction by the aid of the aromatic dihydric alcohol of different substituent groups, the aliphatic dihydric alcohol, supported metal-metal oxide combinations, oxygen or air under the mild conditions with the organic solvents or without solvents to prepare the lactone. The aliphatic dihydric alcohol is used as a substrate, the supported metal-metal oxide combinations are used as the catalysts, and the oxygen or the air is used as an oxidizing agent. The method has the advantages that various shortcomings of the traditional catalysts can be overcome by the aid of catalytic systems, the catalysts are few in usage and are excellent in catalytic activity under the mild conditions and even at the normal temperature, the high catalytic activity and the high selectivity still can be kept even after the catalysts are repeatedly used, economic and environmental protection requirements can be met, the method for preparing the lactone by means of carrying out oxidation reaction on the dihydric alcohol has a broad industrial prospect, and the like.