Abstract: A series of novel Ag₂CO₃/ZnO heterostructures composite photocatalysts were synthesized by hydrothermal method. The prepared photocatalysts were characterized by X-ray diffraction (XRD), Scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscope (FT-IR), and UV-vis diffuse reflectance spectra, respectively. The photocatalytic activity of the prepared samples was evaluated by photocatalytic degradation of methyl orange (MO) under UV light (λ=254nm) irradiation. The different Ag₂CO₃ compound quantity and different hydrothermal temperature of ZnO composite photocatalyst were researched. The results show that the photocatalyst prepared with two-percent of Ag₂CO₃ and 140 ℃ of hydrothermal temperature exhibits the highest photocatalytic activity, owing to the 86.31% of degradation rate. The high photocatalytic performance of the heterostructures composite photocatalysts could be attributed to the strong UV light absorption. A certain amount of Ag₂CO₃ could improve the separation efficiency of the e-/h+ pairs and the physical property of the catalysts.