Supercapacitors have attracted increasing attention due to their widespread applications, such as hybrid electric vehicles, power tools, portable electronic equipment and other devices. Using larger surface area of graphene electrodes and thinner dielectrics to achieve larger capacitances is a new trend for increasing capacitance of supercapacitors. This allows for energy densities greater than those of conventional capacitors and power densities greater than those of batteries.. In this paper, graphene oxide was synthesized by improved Hummers method. polyaniline PANI/grapheneoxide (GO) nanocomposite electrode materials were prepared from aniline (ANI), GO and ammoniumpersulfate (APS) by insitu chemical polymerization in ice bath. GO in composite was reduced for 5h and 20h. The crystal structure and the surface topography of all materials were characterized by Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The electrochemical properties were evaluated by cyclic voltammetry (CV), charge-discharge measurements, electrical impedance spectroscopy (EIS) and a four-point probe, respectively. The results show that with increasing reduction time, the oxygen content on the surface of GO was decreased, leading to increased ID/IG ratio in the Raman spectra of GO and increased conductivity of composite. Consequently, the capacitance properties of RGO/PANI composites could be significantly improved by the reduction of GO for 20h. The GO /PANI composite reduced for 20h had a specific capacitance as high as 1405.68 F/g at scan rate of 1 mV/s compared with 291.73 F/g for pristine graphene film.