Polymer-based thermal conductivity composites composed with nanoscale fillers are promising thermal conductors to dissipate accumulated heat of integrated circuits in electronic devices, while interfacial thermal resistance (ITR) and disordered conductive pathways caused by the size effect of fillers limit their heat transfer performance. Herein, gravitational-driven ice-templated oriental arrangement of ionic liquid (IL) modified microscale carbon fibers (CFs) were conducted to improve thermal conductivity via both weakening phonons scattering effect and forming horizontal orientation heat transfer pathways in composites. The cation-π interaction between CFs and the hydrogen bonding between CFs and epoxy resin induced by IL effectively reduced ITR in composites. As a result, the composite including 22.3 vol% CFs reached a maximum in-plane thermal conductivity of 7.98 W m−1 K−1. The mechanical properties of the composite were also developed. This insight provides a strategy for the construction of high-performance composites with potential applications in thermal management materials.