The invention provides a resin framework monomer taking 2,4-diacetyl-3-(4-bromophenyl)ethyl glutarate as a core. The molecular formula of the resin framework monomer is as shown in a formula I. The invention further provides a preparation method of the resin framework monomer, and the method comprises the following steps: mixing 2,4-diacetyl-3-(4-bromophenyl)ethyl glutarate and aliphatic diamine for modification to generate a reaction core, and performing grafting on the reaction core alternately to generate a 0.5-genreation product, a 1-genreation product, 1.5-genreation product, 2-genreation product and a 2.5-genreation product in sequence and finally generate a 3-genreation product, namely the resin framework monomer, wherein methyl acrylate is adopted as a reactant in reaction processes of half-generation preparation, and aliphatic diamine is adopted as a reactant in reaction processes of whole-generation preparation. The resin framework monomer prepared by the invention has a rigid structural main chain and thus has favorable salt resistance and thermal stability, and the effect is improved when the resin framework monomer is applied in an oilfield oil displacement polymer.