The polyaniline/graphene (PANi/GR) composites were prepared by the in-situ polymerization technique for the counter electrode of a dye-sensitized solar cell. Adding graphene in the polyaniline matrix reduces the charge transfer resistance at the counter-electrode and thus improves the photovoltaic performance of devices. In this work, graphene contents were varied from 6% to 15%. The morphology and the crystallographic structure of PANi/GR composites were examined by Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). The stability and electrochemical activity were investigated by Cyclic Voltammetry (CV) and chronoamperometery. The results indicated that the electrochemical and photovoltaic performances of dye-sensitized solar cells were affected by the graphene contents in composites. The solar cell constructed by PANi/9%GR composite counter-electrode indicated the overall efficiency of 7.45% and the interface resistance (R-ct) between electrolyte and counter-electrode is 20.1 Omega. This performance was slightly lower than platinum-based solar cells (PCE = 7.63% and R-ct = 19.2 Omega) fabricated under similar conditions.