Quantum dot solar cells (QDSCs) are regarded as one of the most efficient devices due to their intermediate band structures. A suitable light-trapping (LT) strategy matching the absorption spectrum is important to improve the photocurrent conversion efficiency of QDSCs. In this paper, we have proposed a design of the periodically patterned top and bottom dielectric nanopyramid arrays for highly efficient light trapping in GaAs-based QDSCs. The dielectric nanopyramid arrays significantly improve the light absorption of QDSCs in the longer wavelength between 0.8 µm and 1.2 µm. In addition, this LT structure ensures a completely flat window layer and back surface field layer while passivating these semiconductor surfaces. For the optimized double-sided structure, the short-circuit current generated by QDSC is 34.32m A/c m 2, where the photocurrent from the quantum dots (QDs) is 5.17m A/c m 2. Compared to the photocurrent of the QDSC without an LT structure, the photocurrent of the double-sided structure is increased by 84%. The QD photocurrent of the double-sided structure is increased by 570% compared to that of the QDSC without the LT structure.