A novel SiO2 hierarchical nanostructure standing on carbon nanowires is synthesized by using the hydrothermal method without any metallic catalysts. Its surface morphology, microstructure and composition are characterized by scanning electron microscopy, high-resolution transmission electron microscope and energy-dispersive spectroscope, respectively. The results show that this new nanostructure is consisted of core-shell-branches C@SiO2/SiO2. The cores are the single-crystalline carbon nanowire, and the shells and branches are the amorphous SiO2. Growth mechanisms are discussed.