The invention provides a method for preparing butadiene by oxidative dehydrogenation of butene. The method comprises a reaction stage and a post-treatment stage. In the reaction stage, multiple adiabatic fixed beds operated in series are adopted, in each adiabatic fixed bed, butene, oxygen-containing gas and water undergo a reaction in the presence of a catalyst, in one adiabatic fixed bed, a diluent for nitrogen and/or carbon dioxide is separately fed and a mole ratio of the fed diluent to oxygen in oxygen-containing gas in the fed materials in the later adiabatic fixed beds is controlled, the oxygen-containing gas is air, oxygen-enriched air or oxygen gas, the oxygen-containing gas in the fed materials in the later adiabatic fixed beds at least contains oxygen-enriched air or oxygen gaswith specific oxygen content, and the reaction effluent from the last adiabatic fixed bed is treated in the post-treatment stage so that a product butene is separated. The whole process has low totalenergy consumption.