The composite material of MoO3/Cd0.5Zn0.5S was synthesized by the one-pot hydrothermal method using MoO3, Cd0.5Zn0.5S and PVP. The structure, morphology and optical properties of the composite were characterized by XRD, XPS, SEM, UV-Vis DRS and PL. Under visible light irradiation, MoO3/Cd0.5Zn0.5S possessed photocatalytic degradation ability for methyl orange, rhodamineB, methylene blue, malachite green and acid fuchsin. Among them, the photocatalytic activity of methyl orange is the best. The experimental results showed that the degradation rate of methyl orange was 98% under the optimal conditions of 60 min, 0.67 g/L 10% Cd0.5Zn0.5S/MoO3 as well as visible light. For photocatalytic degradation methyl orange, reaction rate constant of 10%Cd0.5Zn0.5S/MoO3 was 169 times and 31 times that of MoO3 and Cd0.5Zn0.5S, respectively.