Trace Ag2CO3 (0.5%, 1%, 2%, and 4%) was loaded on commercial TiO2 crystals by a facile precipitation method. The obtained Ag2CO3/TiO2 composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), photolimunescence (PL) spectroscopy, and UV-vis diffuse reflectance spectroscopy (DRS). Under UV light (lambda = 254 nm) or visible light irradiation, the photocatalytic performance of the samples was tested in degradation of methyl orange (MO). Results showed that loading of 1 wt % Ag2CO3 results in the best photocatalytic activity. Under UV or visible light irradiation, the degradation activity of 1%Ag2CO3/TiO2 composite is 6 times that of TiO2 and 4 times that of Ag2CO3 or 3.4 times that of TiO2 and 1.7 times that of Ag2CO3. Reasons for enhanced activity were found that the coupling of Ag2CO3 promoted the visible light absorption and suppressed the recombination rate of e(-)/h(+) pairs. Moreover, more surface OH groups over the Ag2CO3/TiO2 composite can react with the photogenerated h(+) and produce center dot OH radicals to decompose the dye.