Graphitic carbon nitride (g-C₃N₄) nanosheets loaded with WO₃ nanoparticles were prepared via heat treatment of g-C₃N₄ together with WO_x-EDA nanobelts. The thermal treatment temperature and WO_x-EDA precursor play the key role in enhancing the interaction between WO₃ nanoparticles and g-C₃N₄ nanosheets, because the temperature of thermal decomposition of WO_x-EDA (∼400 °C) is close to the thermal exfoliation temperature of g-C₃N₄. The structure evolution and promotion effect of the nanocomposites in photocatalytic performance were well studied. It is found that WO₃ nanoparticles uniformly dispersed on the surface of the g-C₃N₄ nanosheets, and the close integration of WO₃ and g-C₃N₄ lead to the high photocatalytic activity in the degradation of RhB under visible light irradiation. Meanwhile, a larger specific area and increase of visible light absorption are also of benefit to speed up the degradation of organic dye. Also, the mechanism of the photocatalytic reaction and its reutilization properties were investigated.