Designing rationally and controlling precisely the hierarchical nanomaterials are of crucial significance for achieving high-performance nanodevices. Here, substantial SiC nanowires (NWs) with various morphologies and dimensions on carbon fabric were synthesized by regulating the ratio of Si and SiO2 via a simple catalyst-free CVD approach. A wealth of NWs with mean diameter of ∼25 nm and narrow distribution are obtained. The crystallization and growth of SiC NWs converted from self-assembly nanorods on carbon fabric are investigated in detail. Structural evolution experiences amorphous structure, partial crystal, crystal with irregular defects, as well as near-periodical twins. Crystal structure converted from irregular defects to near-periodical twins is ascribed to the release of elastic energy via vapor-solid (VS) mechanism. Electrochemical results display a high areal capacitance of 46.7 mF/cm2 at a scan rate of 0.1 V/s, an almost ideal capacitive behavior as well as robust stability. This areal capacitance is much higher than that of state-of-the art carbon-based supercapacitor electrodes. The electrochemical capacitance property demonstrates SiC NWs on carbon fabric as promising candidates for high-performance supercapacitors.