The invention discloses a polymer solar cell, which comprises a substrate, an anode layer, an anode buffer layer, an active layer and a cathode layer sequentially stacked from bottom to top, wherein the active layer comprises (1) PTB7 or PM7, (2) PC71BM or ITIC, and (3) an additive; the additive comprises a first additive and a second additive, the first additive is 1, 8-diiodooctane, 1, 8-dibromooctane, chloronaphthalene, 1, 8-octanedithiol or diphenyl ether, and the second additive is polyethylene glycol. DIO and PEG double additives are doped in a PTB7:PC71BM mixed solution; the dissociation efficiency of photo-induced excitons of the polymer solar cell, the transport efficiency of charge carriers and the collection efficiency of carriers by an electrode are improved by utilizing the morphology of the active layer improved by the double additives and the conductivity of the anode buffer layer, and the energy conversion efficiency of the polymer solar cell is remarkably improved.