Abstract: Starting from 2,7-dibromofluorene, two aryl substituents were introduced to the 9position of fluorene to replace the commonly used alkyl groups to increase the stability of fluorene. New polymers with excellent thermal and luminescent stability were synthesized using newly designed monomers through the “AB2+AB” approach. The decomposition temperatures of all hyperbranched polymers are above 400 °C. No green emission band was observed after polymer films heated at 200 °C in air for 2 h. Compared with alkyl substituted polyfluorenes, the luminescent stability has a marked improvement. DSC results show that linear polymer and hyperbranched polymers don’t have an obvious phase transition within 300 °C, indicating formation of hyperbranched polyfluorenes amorphous films, which help to improve the emitting efficiency of polyflorenes in film.