A preparation method for a thermally activated delayed fluorescence material, comprising: adding a catalyst, an alkaline substance and a solvent into a first reactant which is a bromide of cyclopentane[def]fluoren-4,8-dione and a second reactant; performing a substitution reaction so as to obtain a reaction solution; and performing impurity removal on the reaction solution so as to obtain the thermally activated delayed fluorescence material having a structural formula of (I). Cyclopentane[def]fluoren-4,8-dione is used as an acceptor unit, reducing the triplet energy level of the acceptor unit, and enhancing the intramolecular charge transfer state property thereof, and achieving red shift of luminescent molecules.