In this work, vanadium pentoxide and reduced graphene oxide (rGO) nanocomposites were synthesized by a simple solvothermal process with subsequent annealing treatment. The study revealed that introducing with a small amount of graphene has a great influence on the V2O5 nanostructure. Adding an appropriate amount of graphite oxide (GO) powder resulted in the formation of rGO substrates via the solvothermal process, which acted as a good dispersant to impede the aggregation of V2O5 blocks. As a result, an ideal morphology of porous V2O5 nanorods dispersed on rGO substrates could be observed. In particular, the nanocomposites possessed a high specific capacitance of 450.5 F/g at a current density of 0.5 A/g, retaining 73.3% of the initial capacitance even at 10 A/g. Symmetric supercapacitors assembled with these electrode materials achieved an excellent energy density of 33.5 Wh/Kg at a power density of 425.6 W/Kg, which is higher than most reported symmetric supercapacitors. Especially, the potential window of the supercapacitor is 0-1.7 V in an electrolyte of 5 M LiNO3, which is also distinctive in the symmetric supercapacitor group.