Abstract: The carb on nantubes/tungsten oxide nanorobs was prepared assisted by ultrasonic field. Thesamples were characterized by scanning electron microscopy (SEM), transmission electron microscopy(TEM) and energy spectrum analyzer (EDS). The results showed that the carbon nantubes disperseuniformly. The tungsten acid attaches to the surface of the carbon nantubes. The carbon nantubes/tungstenoxide nanorobs can be produced after 3 hours sintering at 800 ℃. The photocatalystic activities of the asprepared photocatalyst for methylene blue were studied with 11W fluorescent light as the light source. Theinfluences of the catalyst and the aqua hydrogen dioxide on the degradation rate of the methylene blue bywere studied. The absorbance of the reaction liquid was determined by UV-Vis spectrophotometer. Theresults showed that the methylene blue didn't degrade with catalyst or aqua hydrogen dioxide. Thedegradation rate reaches 95.3 % for 70 min of light with 30 mg of catalyst and 2.5 mL of aqua hydrogendioxide. The catalyst can be duplicated for its stability is good after five times of degradation.