Efficient PbS quantum dot (QD) solar cell with the traditional structure requires an inorganic buffer layer that is usually fabricated at high temperature, which is not compatible with the industrially preferential roll-to-roll fabrication process. Identification of a suitable buffer layer and efficient device construction are thus of particular significance. Herein, we fabricate PbS quantum dot solar cells in an inverted structure using poly(thiophene) (3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) as the anode buffer layer. The resulting devices present a high efficiency of 4.1%, among the best values of inverted PbS QD solar cells. Electrochemical and photoelectric characterizations have shown that, compared with high-temperature annealed nickel oxide (NiO) and vanadium pentoxide (V2O5) layers, the low-temperature processed PEDOT:PSS layer has a more compatible film properties for efficient injection and collection of, charges from PbS QD active layer. Our work provides a promising strategy for fabrication of QD solar cells in an economical and efficient way.