In order to investigate the bimolecular recombination of generated car riers in a bulk heterojunction blend and the effects of acceptor concentration on recombination properties at the donor-acceptor int erface,we fabricated the bulk heterojunction organic solar cells based on compositional blend of P3HT and PCBM.Test results show that the acceptor concentration affects the photoelectric p roperties of bulk heterojunction organic solar cells, the device charge collection,and also the recombin ation loss.It shows a decrease in photocurrent with increasing bias voltage,and the photocurrent decline reflects the recombination loss characteristics of carrier at the donor-acceptor interface.The theoretical analysis further indicates that a ratio between e lectrons in the acceptor to electrons in the donor has a direct relationship with the acceptor concentration,and acceptor concentration changes the size of the bimolecular recombination constant,influencing the recombination properties of carrier.The studies in this paper are useful for further improving the photoelectric c onversion efficiency of organic solar cells.