In this paper, CdSe QDs@UIO-66 composite has been prepared and characterized by PXRD, ICP-AES, UV-visible DRS, BET and TEM. The results show that CdSe QDs are embedded into UIO-66 with high content, small size and high dispersity. The growth of CdSe QDs displays the process from interior to exterior of UIO-66 and the major of generated CdSe QDs is embedded into UIO-66. The photocatalysis of CdSe QDs@UIO-66 composite to RhB under visible-light irradiation shows that coupling semiconductor CdSe QDs and semiconductor UIO-66 apparently enhances the photocatalytic activity and photocatalytic activity is closely related with CdSe QDs content. The photocatalytic stability indicates that the structure of CdSe QDs@UIO-66 composite is unchangeful after reacted and CdSe QDs@UIO-66 composite can be reused several times. The photocatalytic mechanism exhibits that O2−˙ species is responsible for the photocatalytic activity.