TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (claimed): 2,7-Dibromo-9,9-dialkyl silicon fluorene and n-butyllithium are added, in molar ratio of 1:2-1:4, into solvent (A) for dissolution at (-100)-(-25) degrees C, then 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane is added, and reacted for 24-48 hours, to obtain 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane)-9,9-dialkyl silicon fluorene. 1,3-bis(3,4-dialkyl thiophen-2-yl)-5-alkyl-4H-thiofuran(3,4-c)pyrrole-4,6-(5H)-diketone and brominating agent are added into solvent (B) for dissolution, in molar ratio of 1:2-1:3 at 0-30 degrees C for 12-48 hours, to obtain 1,3-bis(5-bromo-3,4-dialkyl thiophen-2-yl)-5-alkyl-4H-thiofuran(3,4-c)pyrrole-4,6-(5H)-diketone. 1,3-bis(5-bromo-3,4-dialkyl thiophen-2-yl)-5-alkyl-4H-thiofuran(3,4-c)pyrrole-4,6-(5H)-diketone and 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane)-9,9-dialkyl silicon fluorene are added into solvent (C) containing catalyst and alkali solution at 65-120 degrees C under oxygen-free environment, and Suzuki reaction is performed for 24-72 hours, to obtain dibenzosilole derivative (I). Preferred Composition: The solvent (A) is tetrahydrofuran, aether, methylene dichloride, chloroform and/or ethyl acetate. The molar amount of 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane is 2-4 times of 2,7-dibromo-9,9-dialkyl silicon fluorene. The brominating agent is N-bromosuccinimide. The solvent (B) is N,N-dimethylformamide, tetrahydrofuran, aether, methylene dichloride, chloroform, ethyl acetate and/or acetic acid. The solvent (C) is tetrahydrofuran, toluene, chloroform and/or ethyl acetate. The catalyst is organic palladium or mixture of organic palladium and ligand of organic phosphor. The amount of catalyst is 0.005-0.1 time of 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane)-9,9-dialkyl silicon fluorene. The alkali solution is aqueous solution of sodium hydroxide, sodium carbonate, sodium bicarbonate or tetraethyl ammonium hydroxide. The molar amount of alkali in alkali solution is 2-20 times of 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane)-9,9-dialkyl silicon fluorene. The organic palladium is tetrakis (triphenylphosphine)palladium(0), tris(dibenzylideneacetone)dipalladium(0) or bis(triphenylphosphine)palladium(II) chloride. The ligand of organic phosphor is tris(o-tolyl)phosphine. Preferred Definitions:    n=20-80.