Hollow silica nanospheres (HSNS) with ultrasmall size distribution (∼20 nm) and hierarchical hollow silica spheres (HHSS) with shells composed of self-assembled HSNS have been successfully synthesized through a novel single-micelle-template approach by using CTAB as the template and octane as a swelling agent. The effect of the volume ratio of octane/water on the preparation of the hollow silica particles was investigated and the prepared samples were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS) and nitrogen sorption analysis. The results demonstrated that the organic solvent octane can lead to the particles changing from conventional ordered mesostructures to individual HSNS (∼20 nm) and an increase in the octane/water ratio will bring about the self-assembly of the HSNS to form HHSS (90–150 nm). The HHSS can effectively load drug molecules for delivery.