TCDD and PCDD are persistent organic pollutants and they have induced a series of severe influences on pro-environment and human health. So how to reduce their harmful effects is the most urgent and tough works we were facing now. In this paper, a novel photoreactor possessing high photocatalytic conversion efficiency of TCDD and PCDD was fabricated with modified photocatalysts which were loaded on the activated carbon fibers. During the photo-conversion process, TCDD and PCDD were enriched on activated carbon fibers first, and then they were photoconversed by modified photocatalysts effectively. The modified photocatalyst was prepared by doping nitrogen into commercial available titania. Analysis by X-ray photoelectron spectroscopy (XPS) indicated that the peak at 396eV is attributed to N bound to Ti atoms, which is the main reason of photocatalytic activity enhancement. For the results of XRD didn’t indicate the formation of Ti-N crystallite, we could deduce the substitution of N for lattice O. A significant shift of the absorption edge to a longer wavelength and a higher absorption in the visible light region were observed. These N-doped TiO₂ powders exhibited excellent photocatalytic activity for the conversion of TCDD and PCDD under irradiation.