Polyimide (PI) film is usually considered as a valuable pyrolysis precursor of graphitized films applied in various electrodes and batteries. In this work, reduced graphene oxide (RGO) sheets were chosen as the catalysts to improve the graphitization properties of PI film. To analyze the structural evaluations, the crystalline growth process with RGO increasing was carefully investigated by transmission electron microscope (TEM) and the crystalline sizes were calculated by X-ray diffraction (XRD) and Raman spectra. The obvious induced effects were confirmed in graphitization of RGO/PI composites at 2300 °C. Finally, the electrical properties of as-prepared RGO/graphite composites were also improved with RGO increasing.