Silver-modified cuprous oxide (Cu₂O) crystals (SMCCs) were successfully created by a facile one-step in-situ Ag-loading reaction under room temperature. The samples were studied by X-ray diffraction, scanning electron microscopy, UV-vis diffuse reflectance spectra and transmission electron microscopy. The photocatalytic performance of the SMCCs were estimated by using methyl orange aqueous solution as a standard pollutant under visible light irradiation. As a result, the SMCCs show a higher photocatalytic activity than the pure phase Cu₂O. The silver nanoparticles which adhered on the surface of Cu₂O of different size and content can greatly effects the photocatalytic efficiency. The enhanced photocatalytic activity owed to the effective charge transfer of excited electron-hole pairs by loading Ag.