In this work, using the sodium thiosulfate and sodium sulfite as the reaction raw materials, the Er and Yb doped ZnS quantum dots were prepared by the hydrothermal method. The phase、morphology and fluorescence performance of ZnS quantum dots were analyzed by XRD, TEM and the fluorescence spectrophotometer. The results showed that both the prepared ZnS∶Er and ZnS∶Er ,Yb were ZnS blende structure, the grain was near spherical and about (5~10) nm in size. The fluorescence spectral showed the ZnS∶Er quantum dots had a strong emission peak for 2H11/2→4I15/2 of Er ion energy level at 530 nm. With the increase of Er content, the fluorescence intensity of ZnS∶ Er quantum dots increased firstly and then decreased. The fluorescence effect was optimal with x(Er)=2% and x(Yb)=1%. When the ZnS quantum dots with the doping amount of 2% of Er and 1% of Yb were coated by SiO2, the surface defects of the quantum dots were suppressed, the luminous peak of Er ion was enhanced obviously, and the luminous intensity was maximum at 1.5% of ethyl silicate coating.