Abstract: Photocatalytic technology can use photogenerated electrons to reduce easily soluble U(Ⅵ) to insoluble U(Ⅳ). In this work, hierarchical macro/mesoporous g-C₃N₄-TiO₂ composites were synthesized without the introduction of organic templates or auxiliary additives, and were used for photocatalytic reduction of U(Ⅵ). The morphology, structure and optical properties of g-C₃N₄-TiO₂ composites were studied by X-ray diffractometer(XRD), scanning electron microscope(SEM), automatic specific surface area physical adsorption instrument(BET), ultraviolet-visible diffuse reflectance spectrometer(UV-vis DRS) and other advanced characterization equipment. The photocatalytic reduction of U(Ⅵ) of g-C₃N₄-TiO₂ composites was studied by photocatalytic experiments. The results show that g-C₃N₄-TiO₂ composites have the advantages of hierarchical macro/mesoporous TiO₂ and g-C₃N₄, not only have a large specific surface area(174.68 m²/g) and pore channels, but also have a wider light absorption range. Therefore, the removal rate of g-C₃N₄-TiO₂ composites on U(Ⅵ) is as high as 98.4% within 15 min. This work provides new ideas for the treatment of uranium-containing radioactive wastewater.