Nanomter WO3 - TiO2 composite photocatalyst were prepared by sol-gel method. X -ray reflection diffraction (XRD) spectra and scanning electron microscope (SEM) have Been used to investigate the structural properties and surface morphology of the composite nanopowder. Photocatalytic degradation experiments for 10mg/L Methyl orange solution were performed to inspect the influence of different preparation conditions on its photocatalytic activity. Methyl orange solution photocatalytic degradation has been heightened with the augment of the WO3 -TiO2 Nanopowder ,but the quality of the Nanopowder has a right numerical value in photocatalytic degradation ; Changing the time, Methyl orange solution photocatalytic degradation has been heightened with the extended time,but the photocatalytic degradation ratio of the Methyl orange solution has a right numerical value with prolonged time ; The resultes showed that the composite WO3 -TiO2 Nanopowder with the highest photocatalytic activity was obtained as the doping amount of钨酸钠= 3% and the highest photocatalytic activity was 94. 8%.