TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (claimed): Organic semiconductor material is prepared by:(A) dissolving 2,7-dibromo-9,9-dialkylfluorene and n-butyllithium into a first solvent with mol ratio of 1:2-1:4 at - 100-- 25 degrees C, and then adding 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolan to react to obtain 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan)-9,9-dialkylfluorene;(B) dissolving 1,3-bis(3,4-alkylthrophene-2-yl)5-alkyl-4H-thiophene (3,4-c)pyrrole-4,6(5H)-dione and a bromating agent into a second solvent with mol ratio of 1:2-1:3 at 0-30 degrees C, and reacting to obtain 1,3-(bromine-3,4-alkylthrophene-2-yl)5-alkyl-4H-thiophene (3,4-c)pyrrole-4,6(5H)-dione; and(C) dissolving 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan)-9,9-dialkylfluorene and 1,3-(bromine-3,4-alkylthrophene-2-yl)5-alkyl-4H-thiophene (3,4-c)pyrrole-4,6(5H)-dione into a third solvent containing catalyst and aqueous alkali with mol ratio of 1:a, and performing Suzuki reaction at 65-120 degrees C to obtain the organic semiconductor material, where a=0.95-1.05.Preferred Component: The mol content of 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolan is 2-4 times greater than that of 2,7-dibromo-9,9-dialkylfluorene and n-butyllithium. The first solvent is tetrahydrofuran, diethyl ether, dichloromethane, trichloromethane or ethyl acetate. The bromating agent is n-bromosuccinimide. The second solvent is N,N-dimethylformamide, tetrahydrofuran, diethyl ether, dichloromethane, trichloromethane, ethyl acetate or acetic acid. The catalyst is tetrakis (triphenylphosphine)palladium, palladium acetate, tricyclohexyl phosphine, tris(dibenzylideneacetone)dipalladium/tri(o-tolyl)phosphine or bis(triphenylphosphine)palladium chloride. The mol content of catalyst is 0.005-0.1 times greater than that of 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan)-9,9-dialkylfluorene. The aqueous alkali is sodium hydroxide aqueous solution, sodium carbonate aqueous solution, sodium bicarbonate aqueous solution or tetraethyl ammonium hydroxide aqueous solution. The mol content of aqueous alkali is 2-20 times greater than that of 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan)-9,9-dialkylfluorene. The third solvent is methylbenzene, tetrahydrofuran, trichloromethane or ethyl acetate. Preferred Definitions:    R 1-R 7=alkyl; and    n=20-800.