The invention belongs to the field of organic luminescent materials, and provides preparation and application of an organic thermally induced delayed fluorescence material containing a 9,9-dimethyl acridine unit. Isophthalonitrile with high eletrophilicity is taken as the electron acceptor, a cyano group with a strong electron-withdrawing performance is introduced, 9,9-dimethyl acridine is taken as the electron donor, and a meta-position connection mode is adopted to obtain the organic micromolecular thermally induced delayed fluorescence material with an excellent luminescence property, and the conventional para-position connection mode is broken through. The organic thermally induced delayed fluorescence material, which contains a 9,9-dimethyl acridine unit and adopts a meta-position connection mode, can be applied to vapor deposition of devices. Meanwhile, the organic thermally induced delayed fluorescence material has the advantages of high yield, high thermal stability, and easy film forming, can be massively produced and used in a large scale, and can be applied to electroluminescent devices to obtain a high efficient electroluminescent performance.