WO3@Graphene (WO3@GR) nanocomposite has been synthesized by using a simple sonochemical method, and the phosphotungstic acid was used as the source of the WO3 nanoparticles. The new catalyst was analyzed by means of FT-IR, XRD, TEM, and SEM-EDX. FT-IR spectrum of the new material reveals that sulfonic acid groups existed on the surface of graphene nanosheets. In addition, TEM image of WO3@GR indicates that the WO3 nano-particles in size of 5-10 nm have an uniform distribution on the surface of the graphene nanosheets. The as-prepared nanocomposite can be used as a catalyst for biomass conversion, and the catalytic hydrolysis of fructose was carried out at different experiment conditions, such as reaction temperature, reaction time and catalyst dosage. HPLC has been used to measure the compounds in product and their yield. It was found that the major products include HMF, formic acid, lactic acid, acetic acid, and maleic acid, and the maximum yield is 43.25% when the reaction was carried out at 160 o C with the ratio of fructose to catalyst is 8 in the presence of 20 ml of water for 2h. The results reveal that the WO3@GR nanocomposite is a potential catalyst for biomass conversion.