Hyperbranched polyglycerols (HYGs) was firstly employed for mediating self-assembly of Fe3O4 nanoparticles to form Fe3O4 nanorods based on an oleic acid (OA)-alcohol-water system. Since the aggregation of Fe3O4 nanoparticles achieved one-by-one assembly induced by HPGs, the resulting Fe3O4 nanorods show a complete structure and high crystallinity, especially when the solvo-hydrothermal process was performed at 180 degrees C for 16h.