Cu₂O-MoO₃ composites has been successfully fabricated by solution-phase reducing method at room temperature. All the powders were characterized by X-rays diffraction (XRD) and scanning electron microscopy (SEM), and explored the catalytic activity for the photocatalytic degradation of methyl orange. The effect of different factors on the degradation was investigated. The best reaction conditions were found out. The results demonstrated that initial concentration of methyl orange is 5 mg/L, the pH is 4, the catalyst dosage is 0.38 g/L and the H2O2 is 1.8 mL, the degradation rate of methyl orange is as high as 95.4% after 30 minutes simulated natural light irradiation.