Efficient and economical technologies are essential to the control of SO2, the emission of which poses serious health concerns and environmental risks. Photocatalysis is an attractive method for reducing SO2 emissions. To reduce energy consumption for excess moisture evaporation, a dry photocatalytic oxidation (DPCO) system was used instead of a traditional gas liquid process in this study. Considering that TiO2 is a widely applied photocatalyst for the purification of gaseous pollutants, this study investigated the photocatalytic removal of SO2 over different TiO2-based nanofibers. Results show that the reduction of SO2 was mainly due to oxidation. Under ultraviolet irradiation, the removal of SO2 was enhanced by the presence of NO2, which was formed by the oxidation of NO. More interestingly, the SO2 removal efficiency remains 100% over cerium-based titania nanofibers with an increase in gas humidity, indicating that this sample has excellent resistance to H2O. This is very beneficial for application in an actual flue gas atmosphere, where H2O is inevitable. In contrast, H2O played a bifacial effect in the photocatalytic removal of SO2 over copper-based titania nanofibers. Under low levels of H2O (<4%), competitive adsorption for active sites leads to the deactivation of photocatalytic activity, while addition of 8% H2O resulted in more SO2 dissolution. Nevertheless, the promoting effect was limited; competitive adsorption was the major factor. Accordingly, the main reaction products are H2SO4 and H2SO3. These indicate that combining photocatalysis technology with TiO2-based nanofibers is a promising strategy for oxidizing SO2 during a DPCO process.