New environmental legislation consider wastewater filtration via surface adsorption and other filtration processes indispensable. Traditional and biological filtration methods for wastewater treatment are not sufficient for the current needs of human society because they reject the highly concentrated wastewater into the environment. One suitable alternative and an industrial solution for wastewater treatment, is the use of advanced oxidation process, which is based on the production of activated species such as hydroxyl radical that filters a wide range of industrial pollutions. The usage of titanium dioxide, is one of the methods of using advanced oxidation process. It is proven that titanium dioxide which is an inorganic photocatalyst, is a simple and effective substance for the removal of organic compounds. In this method of wastewater treatment the release of hydroxyl radicals in titanium dioxide nanoparticles occurred in a UVA wavelength, less than 388 nm. These membranes are very porous and their pores are interconnected. In this research, titanium dioxide nanoparticles were created on polyacrylonitrile nanofiber membranes via sol-gel process. Filtration experiments are categorized into two methods. First, immersing without external pressure and second, using cross-flow process. In all the samples, the retention time of the dye was 24 hours and the electrospinning time of nanofiber was considered 10 hours. In the immersing experiment a 16 cm2 of the filter structure containing a non-woven polyurethane-carbon substrate, polyacrylonitrile nanofiber and titanium dioxide nanoparticles was immersed in 100 cc of methylene blue as the dye solution. Simultaneously the set was put on the UV light with wavelength of 254 nm and the concentration of dye solution was measured every 20 minutes. The filtration efficiency was calculated via Langmuir-Hinshelwood pseudo-first order equations. It was noted that in the two immersing and cross-flow processes, the filtration efficiency of samples using titanium dioxide under ultraviolet beams was higher than that of the samples without titanium dioxide and without the presence of the mentioned beams. Also in comparison to the cross-flow system and the immersing one, with the same assumptions, degradation efficiency of the cross-flow system was higher. In the cross-flow test, the effect of three variables; pressure on the membrane, initial concentration of dye solution and pH of the dye solution was studied with sampling intervals of 5 minutes. In the pressure test, the applied pressures were 1.3, 1.5 and 1.7 bar in the fixed pH of 6.4 and with initial dye solution concentration of 40 ?M. It was noted that the best efficiency was related to the 1.5 bar pressure. In the concentration test, the initial concentrations were considered 45, 50 and 60 ?M on fixed pH of 6.4. It was shown that the best efficiency belonged to the 40 ?M initial concentration. In pH test, the prepared pH values were 4.1, 6.4 and 10.5 with initial dye solution concentration of 40 ?M. It was observed that the best efficiency belonged to the pH of 4.1. Key words: titanium dioxide, photocatalyst, filtration, cross-flow, nanofiber.