In this paper, we demonstrated an enhanced performance of polymer solar cells by incorporating functionalized single-walled carbon nanotubes (SWCNTs) decorated with CdSe/ZnS core-shell colloidal quantum dots (CQDs) into copolymers of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) as active layer. Short-circuit current density and power conversion efficiency of the ITO/PEDOT:PSS/P3HT:PCBM:(CdSe/ZnS-SWCNTs)/Al solar cells can be enhanced by more than 31 and 23 %, respectively, as compared with the control device ITO/PEDOT:PSS/P3HT:PCBM/Al. This enhancement is due to the high electron-transporting ability of SWCNTs and the increased absorption of CdSe/ZnS CQD in visible region. It shows an applicable way to improve the efficiency of polymer solar cells by incorporating suitable quantity of CQDs-decorated SWCNTs with suitable kinds of CQDs and suitable acid treatment to the SWCNTs.