Composite film of graphene oxide (GO) and polyaniline (PANI) nanofibers is synthesized by in situ polymerization of aniline monomer in the GO suspension (GO/PANI composite). The morphology of the composite is examined by scanning electron microscopy (SEM) and transition electron microscopy (TEM). GO nanosheets are homogeneously coated by PANI nanofibers with diameter of 45 nm. Electrochemical performances are characterized by cyclic voltammetry (CV) and galvanostatic charge/discharge techniques. Supercapacitors based on the GO/PANI conductive composite exhibit high specific capacitance (676 F/g) at a discharge current density of 1.0 A/g in 1 M H2SO4 solution, which is much higher than PANI electrode (230 F/g). The excellent performance is attributed to the synergetic effect of GO and PANI nanofibers, which can shorten ion diffusion length and make higher materials utilization. Moreover, the composite electrode presents excellent long cycle life during charge/discharge processes. After 1000 cycles, the specific capacitance decreases 9% of initial capacitance compared to 32% for PANI nanofibers. This technique provides a feasible solution for developing high performance electrical energy storage devices.