Abstract: The geological conditions of thermally altered coal are obviously different from those of normal metamorphic coal. Due to the influence of direct contacted intrusion, the thermally altered coal has undergone a process with rapid heating and slow cooling, on the other hand, it is also affected by additional stress caused by the contact extrusion of the intrusion, which also makes the thermally altered coal significantly different from the normal metamorphic coal in terms of carbon nanostructure changes. In order to reveal the particularity of carbon nanostructures in the thermally altered coals, the carbon nanostructures in the thermally altered coals were systematically analyzed based on the previous studies by our research group and other researchers. The evolution of microcrystalline structure parameters for the thermally altered coal was studied, and the types and its genesis of carbon nanostructures in the thermally altered coal were analyzed with the XRD and HRTEM methods. The results show that compared with the metamorphic coal, the interlayer spacing of the thermally altered coal is closer to that of the graphite crystallites. When the vitrinite reflectance is less than 10%, the interlayer spacing and L_a/L_c of the thermally altered coal show three-stage changes. In addition, four carbon nanostructures were identified in the thermally altered coal, including disordered aromatic cluster structure, aromatic concentric ring structure, turbostratic carbon structure, and graphitic-like structure. Among them, the graphitic-like structures in the thermally altered coal mainly appear at the edges of particles, on the extruded surfaces of micro-components, and at the edges of pores and fissures, which is related to the internal stress of the particles. Compared with the other three carbon nanostructures, the graphite-like structures have better orientation and longer lattice fringe length. Different from the graphite-like structure formed by the heating of normal metamorphic coal, the graphite-like structure at the edge of thermally altered coal particles has smaller interlayer spacing and greater La. Based on this, graphene can be prepared from the thermally altered coal by the improved Hummers method with obviously defects, so a further in-depth and detailed research is urgently needed.