[en] The ternary composite photocatalyst Au/Bi₂MoO₆/Bi₂WO₆ has been successfully synthesized by a facile hydrothermal process and microwave-assisted chemical reduction method for the first time. A series of characterization results reveal that Au nanoparticles are uniformly dispersed on the surface of Bi₂MoO₆/Bi₂WO₆ microspheres. The unique photocatalytic performance of the novel composite material is evaluated by the photocatalytic removal of NO gas at ppb levels under visible light irradiation. The photocatalytic removal rate of NO gas in the presence of Au/Bi₂MoO₆/Bi₂WO₆ sample is the highest, which directly attributes to the effective separation of photoinduced charge carriers through the formation of the heterojunction and the Schottky junction at the interface between Au nanoparticles and Bi₂MoO₆ or Bi₂WO₆. Additionally, it is indicated that the h ⁺ and $\cdot <!--\; ???\; -->{\text{O}}_2^{-<!--\; ???\; -->}$ play indispensable role in photocatalytic process by free radicals trapping experiments and the oxidation products of NO gas on the surface of the catalysts are nitrate by drawing the standard curve of total N content in nitrate. Meanwhile, a possible mechanism for the photocatalytic activity enhancement of the Au/Bi₂MoO₆/Bi₂WO₆ composites is proposed. These results demonstrate that the Au/Bi₂MoO₆/Bi₂WO₆ photocatalyst is a promising candidate for indoor air purification under solar light irradiation. (paper)