β-SiC nanometer whiskers were prepared in a double heating furnace that is composed of the interior and exterior heating systems. The SiO2 nanometer powder and char pyrolyzed from phenol formaldehyde resin were used as starting materials. The effects of sintering temperature and holding time on β-SiC nanometer whiskers were investigated and the synthetic mechanism was studied. It was revealed that the β-SiC nanometer whiskers, with the diameter of 50-80nm and the aspect ratio of 50-300, can be prepared at 1300°C for 60 min. The purity of the β-SiC nanometer whiskers is about 99%.