The invention relates to organic compounds using fluorene as a core, a preparation method of the compounds and an application of the compounds in an organic light emission diode (OLED) device. The compounds have a following structure: the fluorene is connected with a dibenzo five-membered ring and ring structure through a carbon-carbon bond, the carbon-carbon bond connection not only improves the chemical stability of the material, but also avoids exposure of active positions of a branched chain group, and the whole molecule is a larger rigid structure and has a higher triplet state energy level (T1); the compounds have large steric hindrance, are not easy to rotate, and have a more stable stereoscopic space structure, so that the compounds have a higher glass transition temperature and molecular thermal stability; in addition, HOMO and LUMO distribution positions of the compounds are separated from each other, so that the compounds have suitable HOMO and LUMO energy levels; therefore, the compounds can effectively improve the luminous efficiency and the service life of the device after being applied to the OLED device.