The invention relates to a preparation method for aldehyde or alkone, in particular to a method for preparing aldehyde or alkone by oxygen catalysis and alcohol oxidation under the mild condition. Themethod comprises the following steps: according to the 5 mmol of reaction substrate, 1-8 percent of 2,2,6,6-tetramethylpiperidine-oxygen radical (TEMPO) or a derivative thereof, 4-20 percent of halogen-containing compound and 4-20 percent of nitric acid or nitrate are taken as the catalysts, 0.1-0.8 MPa oxygen or air is taken as the oxidant, then the reaction is carried out for 1-36 h at the temperature of 0-80 DEG C, a series of alcohols can be oxidized into aldehyde or alkone with high selectivity, a catalyst TEMPO and the derivative thereof can be circularly and alternately used, the turn-over number (TON) is up to 800 and the cost is greatly reduced. The invention has the advantages of safer reagent with lower price, wider applicability of the substrate, mild reaction conditions, convenient product separation, no pollution to the environment, easy industrialization, and the like.