In this paper, we report on a novel photocatalytic reactor having 547 pieces of TiO2-nanofilm-modified capillaries, which is derived from a microstructured polymer optical fiber(MPOF) preform. TiO2-film-modified MPOF preform is obtained by directly inhaling P25-doped TiO2 sol into array holes of MPOF and forming TiO2 film on their side walls. The MPOF perform acts as not only a light-transmitting media(rolling-up thin film waveguide, collecting and transmitting light into the TiO2thin film), but also a TiO2supporting and waste-water pipe to supply for photocatalytic degradation of toxic organic solute. Methylene blue(MB) is chosen as a model contaminant in water. The effects of loading quantity of TiO2, pH of MB and initial concentration of MB on photocatalytic degradation are investigated. The photocatalytic reactor has so large surface area for TiO2 loading that photodegradation efficiency is enhanced. As far as we know, the photocatalytic reactor with functions of collecting and transmitting light, conveying matter and loading catalyst has not been reported before.