The invention relates to a catalyst for preparing divinylbenzene and a preparation method of the catalyst. The invention mainly solves the problems that the activity of a catalyst is lower and the ratio of a monoene to a diene is high in the prior art; and the invention better solves the above technical problems through adopting the technical scheme that the catalyst used for preparing the divinylbenzene by dehydrogenation of diethylbenzene comprises the following components in percentage by weight: (a) 65-81% of Fe2O3, (b) 6-14% of K2O, (c) 8-14% of CeO2, (d) 0.5-5% of MoO3, (e) 0.5-5% of analkaline earth metal oxide, and (f) 0.1-3.0% of at least one or more selected from NiO, CuO and ZnO, wherein a raw material of the Fe2O3 is from small-grain iron oxide; and the roasting atmosphere andthe flow quantity during the preparation of the catalyst can be adjusted and controlled. The catalyst provided by the invention can be used in the industrial production of preparing the divinylbenzene by dehydrogenation of the diethylbenzene.