CuPcC60 mixed-layer heterojunction organic photovoltaic devices (OPV) and the different performance with the double-layer device is investigated. The results suggest that OPV with the mixed layer has the enhanced device performance, and the open circuit voltage, short circuit current density, the power conversion efficiency and fill factor have been improved, respectively, from CuPc-C60 double-layer structure devices 0.39 V, 1.92 mA/cm2 and 0.36%, 0.48 to CuPcC60 mixed layer devices 0.48 V, 2.21 mA/cm2 and 0.54%, 0.51. The properties of donor-acceptor (D/A) and organic/metal interfaces are studied according to the integer charge transfer model, the open-circuit voltage enhancement of mixed-layer device is due to the increment of HOMO(D)-LUMO(A) offset. The short-circuit current density increase is attributed to the enhancement of the mixed layer heterojunction organic photovoltaic devices D/A interfaces and the increment of HOMO(D)-LUMO(A) offset, leading to the higher photo generated exciton dissociation.