Abstract：This research explores graphite and its intercalation with FeCl3 , aiming to uncover the mechanisms underlying the extremely low cross-plane thermal conductivity observed in GICs; experiments. In this study, we employed non-equilibrium molecular dynamics simulations to investigate the thermal conductivity of FeCl 3 -graphite intercalation compounds (GIC) with various nanostructures, including different stages, thickness, and filling factor. Stage, refers to the number of graphene layers sandwiched between neighboring intercalate layers. The present work provides valuable insights into modulating the thermal properties of graphite by tuning phonon wave nature at room temperature with intercalated layered material．The observed decreasing-increasing thermal conductivity trend affirm the existence of coherent phonon transport at low stages.