The invention discloses a method for preparing a rubber vulcanization accelerator DM by an oxygen process. The method comprises the following steps: a solvent and a raw material benzothiazolethiol M are added in a reaction vessel, then a catalyst is introduced into the reaction vessel, then the materials are reacted when the oxygen introduced into the reaction vessel reaches a certain pressure, the introduction of the oxygen stops, and the reaction is completed; and a crude product 2,2'-dithiobis(benzothiazole) DM; filtering the crude product DM, and drying the filtered product to obtain the product 2,2'-dithiobis(benzothiazole) DM. The method has the advantages of simpleness, low pressure, low temperature, fast reaction speed, low cost, and easy industrial production, water used by the method is recyclable, the product quality is high, yield is high, no three waste is discharged during a synthesis process, and the method has obvious economic benefit and social benefit.