Multilayer graphene (MLG) with a thickness of about 100 nm has proved to be a promising smart thermal surface material with excellent tunability of emissivity, but the performance of MLG will deteriorate significantly with the further increase of film thickness. In this study, mid-infrared radiation modulators based on 500 nm-thick graphite thin films (NGF) were prepared and their infrared radiation performance through ionic liquid intercalation was studied. The experimental results show that modulation depth of NGF with a large number of crumples on the surface prepared under different hydrogen flow rates can reach 0.32–0.37, which is comparable to that of commercial MLG with a thickness of 100 nm. The numerical simulation results show that crumpled surface morphology of NGF is very beneficial to the improvement of the electrically controlled thermal radiation performance, and the crumpled graphene/graphite film has a greater emissivity modulation depth than the flat film. The results can provide inspiration for improving the thermal radiation modulation capability of graphene/graphite thin films through morphology control, thus promoting the application of graphene/graphite in thermal camouflage, radiative cooling, personal thermal management and infrared communication.