Abstract: Graphitized polyimide strips act as bridges between graphene nanoribbons to form macro-scale graphitized graphene/polyimide films. The effect of the sizes of the two components was investigated by non-equilibrium molecular dynamics simulation using the optimized Tersoff molecular force field. Results indicate that the thermal conductivity of the graphene nanoribbon increases almost linearly with length for lengths below 800 nm, but increases as a power function and converges to about 4 300 W/(m·K) above this. The heat conduction between graphene ribbons in the graphitized graphene/polyimide films is improved by increasing the number or width of the graphitized polyimide strips, but is lowered by increasing their length.