Type-Ⅱ core/shell quantum dots enable an enhanced electron injection rate and retard the charge recombination process because of the spatial separation of electron and hole[1,2].Furthermore, expanded light absorption can be observed in type-Ⅱ core/shell quantum dots due to "spatially indirect" energy gap [3], which is beneficial to their application for solar cells.In present work, CdxZn1-xTe-CdS quantum dots with Type-Ⅱ core/shell structure were prepared by an aqueous phase process using 3-mercaptopropionic acid as a stabilizing agent.We investigated the composition of Zn and Cd in CdxZn1-xTe quantum dots by using X-ray photoelectron spectrometer.The X-ray diffraction (XRD) pattems confirmed the cubic zinc blende structure of CdxZn1-xTe quantum dots.We discovered that the dispersibility of CdxZn1-xTe-CdS quantum dots was improved compared to the CdxZn1-xTe quantum dots by using transmission electron microscope (TEM).All samples had a well particle size distribution, which was also confirmed by the obvious absorbance peaks and the narrow FWHM (full width at half maximum) of fluorescence peaks.The particle size of core was about 3 nm while the shell thickness was about 0.9 urn.In addition, the absorption peak and fluorescence peak of CdxZn1-xTe-CdS quantum dot shift towards long-wavelength region compared to CdxZn1-xTe quantum dot as Fig.1 shows, which might be caused by "spatially indirect" energy gap.