The present invention discloses a ternary polymer solar cell. A photoactive layer of the ternary polymer solar cell includes two non-fullerene electron acceptors with large planarity. The weight percentage composition of the photoactive layer in the ternary polymer solar cell is: 41.6-50% of polymer electron donor, 0-50% of polymer electron acceptor, and 0-50% of non-fullerene perylene diimide (PDI) electron acceptor. The non-fullerene PDI electron acceptor is added into the photoactive layer to broaden the spectral absorption of the photoactive layer, improve the phase separation of the photoactive layer and inhibit the recombination of bimolecular charges, resulting in more efficient generation and transport of charges, thereby increasing a short-circuit current density of the ternary polymer solar cell device, and finally improving the power conversion efficiency of the ternary polymer solar cell device. Moreover, a new direction is provided for the selection of the all-polymer non-fullerene acceptor.