Novel noncovalently connected water-soluble nanoparticles containing hydroxyl-capped polyfluorene (PFOH) and poly(acrylic acid) (PAA) were obtained and characterized. These nanoparticles were quite stable in water and no precipitate was observed after weeks. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and laser light scattering (DLS) were used to confirm the morphology of the PFOH/PAA nanoparticles. Their optical properties were investigated and showed the similar optoelectronic properties with PFOH solid film.