TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (claimed): A thiophene compound of formula (A) and thiazole compound of formula (B) are mixed with organic solvent in presence of catalyst under anaerobic condition and inert gas, reacted at 60-120 degrees C for 24-72 hours by still coupling reaction, and separated and purified, to obtain thiazole-dibenzothiophene-benzodiazepin-thiophene polymer (I). Preferred Composition: The catalyst is bis(triphenylphosphine) palladium dichloride, tetrakis (triphenylphosphine) palladium, tris(dibenzylideneacetone) dipalladium and/or tri-o-tolylphosphine. The content of compound (A) with respect to catalyst is 0.01-5 %mol. The content of tris(dibenzylideneacetone) dipalladium with respect to tris(dibenzylideneacetone) dipalladium and tri-o-tolylphosphine is 0.01-5 %mol. The molar ratio of tris(dibenzylideneacetone) dipalladium and tri-o-tolylphosphine is 1:2-1:20. Preferred Process: The compound (A) is obtained by reacting N-bromosuccinimide and thiophene compound of formula (e) with dimethyl formamide at room temperature for 15 hours by bromination reaction under the protection of light. The molar ratio of N-bromosuccinimide and compound (e) is 3:1. The compound (e) is obtained by trifluoromethanesulfonic acid and thiophene compound of formula (d) with phosphorus pentoxide at room temperature for 72 hours, pouring into ice-water bath, precipitated, adding pyridine, and refluxing at 110 degrees C for 12 hours. The molar ratio of trifluoromethanesulfonic acid, compound (d) and phosphorus pentoxide is 1.5:1-2:1. The compound (d) is obtained by reacting thiophene compound of formula (b) and methylsulfinyl compound of formula (c) with solvent at 80 degrees C for 48 hours by Stille coupling reaction under an inert gas and anaerobic condition, and adding catalyst. The molar ratio of compound (b), methylsulfinyl compound (c) and solvent is 1:2-1:2.5. The compound (b) is obtained by reacting tetrahydrofuran and thiophene compound of formula (a) under the protection of inert gas, cooling to -78 degrees C, slowly dripping n-butyl lithium, adding trimethyltin chloride, and reacting at room temperature for 0.5-24 hours. The compound (B) is obtained by mixing thiazole compound of formula (C) and anhydrous tetrahydrofuran under inert gas atmosphere, cooling to -78 degrees C, slowly dripping n-butyl lithium, stirring at -78 degrees C for 2-3 hours, adding trimethyltin chloride, and reacting at room temperature for 0.5-1 hour.