The invention discloses a method for preparing a CO2 oxidization ethylbenzene dehydrogenation catalyst by a combustion decomposition method. The catalyst comprises active ingredient and assisted component, wherein the active ingredient is V2O5, and the assisted component is Al2O3 or compound of Al2O3 and any out of CeO2, ZrO2 and cerium-zirconium composite oxide; the catalyst is prepared by the combustion decomposition method by taking amino acid, sugar, polyethylene glycol, polyvinyl alcohol, methyl methacrylate or carboxymethyl cellulose as a pore-forming agent. The method is convenient to operate, short in reaction time, low in resultant temperature and simple in equipment; the prepared catalyst can be evenly dispersed, and is used for catalyzing CO2 oxidization ethylbenzene dehydrogenation to prepare styrene; the conversion rate of ethylbenzene and the selectivity of the styrene are higher.