A novel high-performance polyindole containing a pyridine ring (P1)was successfully prepared by the catalyst-free nucleophilic substitution polycondensation of 4-hydroxyindole with 2,6-difluoropyridine via a C?N and C?O coupling reaction process. This semirigid polyindole P1 exhibits good thermal stability, and it can be dissolved well in common organic solvents. Fluorescent spectral studies indicate that the resulting polymer shows blue-light emission at 402nm due to the effect of intramolecular charge transfer caused by the donor?acceptor interaction between its indole and pyridine units. Moreover, the fluorescence intensity of P1 could be altered by protonation and deprotonation. Such behaviour enables it to be utilized as one kind of acid response fluorescent polymer sensor.