In this article, the PEDOT:PSS doped with sorbitol film is fabricated on an ITO substrate by blending-spin coating method and used as a hole-extraction layer for organic solar cell (OSC). The effect of sorbitol concentration on the photovoltaic performance of the device is investigated based on P3HT:PCBM blend. Compared with a pristine device (i.e., without sorbitol), the sorbitol-doped (8wt %) OSC shows that the short-circuit current density, the fill factor and the power conversion efficiency are inereased from 8.82 to 9.03mA/cm2, 0.43 to 0.474 and 2.12% to 2.39 % (i.e., by about 13%), respectively. The canse of the improvement on performance of the device is discussed, showing that the increase in conductivity and transmittance of composite films is due to the improvement on OSC performances achieved through the incorporation of sorbitol into hole-extraction layer of PEDOT:PSS. The former leads to a lower series resistance of the device, while the latter gives rise to the improvement on the photo-induced carriers of the photovoltaics cells.