Thermal reduced graphene oxide (TRG) was performed to obtain the TRG/polystyrene (TRG/PS) composite fibers by solution blending followed by electrospinning technique. And then the thermally conductive TRG/PS nanocomposites were fabricated via hot press method. The thermally conductive coefficient (λ), thermal diffusion coefficient (α), glass transition temperature (T_g) and heat-resistance index (T_HRI) of the obtained TRG/PS nanocomposites were all improved with the increasing addition of TRG. The addition of 15 wt% TRG could increase the λ value of pure PS from 0.226 W/mK to 0.689 W/mK, a value from 0.2157 mm²/s to 0.6545mm²/s, Tg value from 90.3 °C to 95.0 °C and THRI value from 184.2 °C to 194.3 °C.