Two precursors, Tungstic acid/DWCNTs and pure tungstic acid, prepared by liquid phase method, were calcinated at 700 ℃for 2h at nitrogen atmosphere. Therefore, WO3/DWCNTs and WO3 powder were obtained respectively. The structure and morphology of as-synthesized products were characterized by powder X-ray diffraction (XRD) and Scanning electron microscope (SEM). The photocatalytic activity of the samples was evaluated by photocatalytic degradation of the methylene blue under visible light (11W) irridation. The clear upper layer solution was analyzed by a Milton Roy Spectronic 3000 Array spectrophotometer (New York, USA).The photocatalytic degradation rate of the samples were calculated according to the lambert beer''s law. The degradation rate of WO3/DWCNTs and pure WO3 is 87.50% and 25.39% respectively under photocatalytic degradation for 30 min. Results show that as the size of particles decreases, the specific surface area increases, and the adsorption capability of WO3/DWCNTs is improved; all these effects are ascribed to the addition of DWCNTs.Therefore, the WO3/DWCNTs composite photocatalyst exhibits much higher photocatalytic activity than that of pure WO3.