We report here a new route to prepare nanocrystalline β-silicon carbide with high specific surface areas and mesoporosity. The preparation method was via the reaction of ordered mesoporous carbons (OMCs, carbon replicas of MCM-48, SBA-15 and KIT-6) with silicon powder at the temperature of 1200–1300 °C, which is below the melting point of silicon, 1420 °C. The SiC samples were characterized by XRD, SEM, TEM, N2 adsorption and other techniques, which showed that the SiC samples were nanocrystalline and had a high surface area of up to 147 m2 g−1 and a mesoporosity in the range of 5–40 nm. In addition, the silicon vapor infiltration method at a temperature beyond 1420 °C was also brought into comparison.