Abstract: The topological microstructure of micro-coiled carbon fibers (MCFs) before and after high temperature treatment (HTT) was explored and characterized. Results suggested that as-grown MCFs had an annular ring-like structure in the cross section and a herringbone-like structure in the longitudinal section, but the orientation range of graphitic domains was wide. After HTT, the coiled fibers consisted of stacked pyramidal prisms of ordered graphitic domains. The apparent morphology of the coiled fibers is a uniform spiral prism. The evolvement of the microstructure of MCFs after HTT was also confirmed by X-ray diffraction and Raman spectroscopy. The topological microstructure provides a reliable reference for the prediction of properties and projected applications of the MCFs.