<p>Precursor conversion is a primary method for preparing SiC ceramics. However, this approach typically results in unavoidable residual carbon in SiC ceramics, which significantly affects their properties. In this study, we utilized nano metal Ni to exhaust residual carbon in precursor-derived SiC and transformed it into carbon nanotubes (CNTs). During the pyrolysis stage, the metal Ni converted into Ni₂Si, which catalyzed the formation of CNTs. Although gaseous hydrocarbon compounds (CH₄, C₂H₄ and C₃H₅) were released in the pyrolysis range of 400–700&#xa0;°C, the carbon source of CNTs originated from both the residual carbon in the precursor-derived SiC and the carbon byproduct after the reaction between metal Ni and SiC. The conversion of residual amorphous carbon into CNTs facilitated the crystallization of precursor-derived SiC. In addition, the introduction of metal Ni was beneficial for improving the thermal conductivity and electrical conductivity of precursor-derived SiC. Based on the carbon source and growth phenomenon of CNTs, the growth mode of CNTs has also been inferred.</p>