Using white granulated sugar (C12H22O11 ) and silica (SiO2 ) nanopowder as the precursor, with the assistance of ammonium chloride (NH4Cl) foaming agent, we have created SiC/C nanocomposites with various mesoporous by changing the proportion of precursors via a carbothermal reduction technique. The crystalline structure, surface morphology, microstructure and component ratio of the SiC/C nanocomposites were thoroughly characterized by using XRD, Raman, Micro-CT, SEM and TEM. Defined by the foaming agent, the carbon matrix consists of highly graphitized porous structure, whilst the reinforcing SiC phase is made of 3C (beta-type) SiC nanowires with a preferred growth direction of [111] and twin structure. At higher carbon ratio, the diameter of the SiC nanowires tend to increase to form larger whiskers. These nanowires possess the sizes of 20-60 nm in diameter and 20-30 mu m in length.