Abstract: A new type π-conjugated copolymer（4-methyl-6-(7-methyl-9,9-dioctyl-9H-fluoren-2-yl) pyri-midin-2-amine ）was prepared between 2,2′-(9,9-dioctyl-9H-fluorene-2,7-diyl) bis (4,4,5,5-tetramethyl-1,3,2-dioxaborolane) and 2-amino-4,6-diiodopyrimidine by Suzuki polycondensation . The structure of the copolymer was characterized by FT-IR, 1H-NMR, UV-Vis spectroscopy, fluorescence spectroscopy, cyclic voltammetry and thermal analysis. Results showed that the derived copolymer exhibited good thermal stability. The copolymer with UV-Vis absorption peak at 390 nm, and PL emission peak at 462 nm and 496 nm, emitted yello green light at the wavelength of the absorption maxima. The copolymer displayed acidichromic properties when protonated with CF3COOH acid in chloroform solutions and the red-shifted peaks were observed from 390 nm to 433 nm. The color of the chloroform CF3COOH solution changed from pale yellow to green.