A fluorene copolymer, method for preparation thereof, and use thereof are provided. Said fluorene copolymer comprises copolymer represented by formula (I), wherein R1-R2, R5-R8 are selected from H or C1-C20 alkyl, R3-R4 are selected from H, C1-C20 alkyl, C1-C20 alkoxyl, phenyl or phenoxyl, x+y=1, x≠0, y≠0; n is an integer of 1 to 200, Ar1 is thiophene unit-containing group. On account of thiophene unit and thienopyrazine unit, the fluorene copolymer has wide spectrum response range and favorable stability.