Abstract: ZnS photocatalyst was synthesized in the presence of surfactant cetyltrimethyl ammonium bromide(CTAB).The results of XRD and TEM indicate that the sizes of the ZnS particles obtained are uniform and there is no aggregation phenomenon.The average size of the ZnS particles is about 3.5 nm.The investigation results of the photodegradation efficiency of the different dyes under the UV light irradiation in the presence of photocatalyst ZnS indicate that the photodegradation efficiency of azo dyes with the -N=N- group,such as methyl orange(MO),acid yellow(AY) and acid organgeII(AOII) on the ZnS photocatalyst in 60 min is as high as 88%,illustrating that the dyes with the -N=N- group is easy to be degraded.In addition,the light absorption properties of the dye molecules also play a certain role.Both xylenol organge(XO) and methylene blue(MB) molecules do not contain the -N=N- group.However,the photodegradation efficiencies of XO is as high as about 59.63% due to the largest absorption peak of XO located at 430 nm.Whereas the photodegradation efficiencies of MB is very low due to the largest absorption peak of MB located at 664 nm.