A method for preparing polymer solar cell, comprising: providing a clean glass substrate and then preparing a cathode, an electronic buffer layer and an active layer successively on the glass substrate; preparing an anode on the active layer by the following steps: dissolving poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate in chlorobenzene to obtain a solution of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate, where a weight of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate are in a ratio 2:1-6:1, and a percentage of poly(3,4-ethylenedioxythiophene) by weight of the solution of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate is in a range of 1%-5%; dissolving zinc oxide in acetic acid to obtain a zinc oxide solution with a concentration of 0.05g/ml-0.6g/ml; mixing the zinc oxide solution and the solution of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate in a volume ratio 1:10-3:4 to obtain a mixed solution, where a weight of zinc oxide and poly(3,4-ethylenedioxythiophene) are in a ratio 0.75:1-6:1; spin-coating the mixed solution on the active layer, and then drying to obtain the anode; obtaining a polymer solar cell. providing a clean glass substrate and then preparing a cathode, an electronic buffer layer and an active layer successively on the glass substrate; preparing an anode on the active layer by the following steps: dissolving poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate in chlorobenzene to obtain a solution of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate, where a weight of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate are in a ratio 2:1-6:1, and a percentage of poly(3,4-ethylenedioxythiophene) by weight of the solution of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate is in a range of 1%-5%; dissolving zinc oxide in acetic acid to obtain a zinc oxide solution with a concentration of 0.05g/ml-0.6g/ml; mixing the zinc oxide solution and the solution of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate in a volume ratio 1:10-3:4 to obtain a mixed solution, where a weight of zinc oxide and poly(3,4-ethylenedioxythiophene) are in a ratio 0.75:1-6:1; spin-coating the mixed solution on the active layer, and then drying to obtain the anode; dissolving poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate in chlorobenzene to obtain a solution of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate, where a weight of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate are in a ratio 2:1-6:1, and a percentage of poly(3,4-ethylenedioxythiophene) by weight of the solution of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate is in a range of 1%-5%; dissolving zinc oxide in acetic acid to obtain a zinc oxide solution with a concentration of 0.05g/ml-0.6g/ml; mixing the zinc oxide solution and the solution of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate in a volume ratio 1:10-3:4 to obtain a mixed solution, where a weight of zinc oxide and poly(3,4-ethylenedioxythiophene) are in a ratio 0.75:1-6:1; spin-coating the mixed solution on the active layer, and then drying to obtain the anode; obtaining a polymer solar cell.