Abstract: The spherical ZnxCd1-xS nanocrystals with controllable morphology were successfully prepared by liquid phase synthesis method.The prepared samples was characterized by many methods,including X-ray diffraction (XRD),ultraviolet visible diffuse reflectance spectroscopy (UV-DRS),X-ray photoelectron spectroscopy (XPS),scanning electron microscopy (SEM) and transmission electron microscopy (TEM).Under the simulated sunlight irradiation,spherical ZnxCd1-xS nanocrystals show a high catalytic activity for the photocatalytic degradation of methylene blue (MB) aqueous solution,especially,the degradation of MB was 95% in 120 minutes for the Zn0.5Cd0.5S sample.With the increase amount of Cd2+ doping,the absorption of ZnxCd1-xS nanocrystals on visible light is stronger than that of pure ZnS,which leads to a higher activity of ZnxCd1-xS to degrade organic pollutants under the sunlight.The results of this paper show that the spherical ZnxCd1-xS nanocrystals are a promising photocatalyst.