A novel BiVO4 hierarchical nanostructure assembled by nanorods was realized via a facile and additive-free solvothermal method. Based on the electron microscope observations, the growth of such architectures with "rod to dumbbell to sphere" transformation has been proposed as a crystal splitting growth process. Ethylene glycol (EG) instead of organic surfactant played an important dual role during the process. Different shapes were obtained by controlling the synthetic parameters. The as-prepared BiVO4 hierarchical nanostructures exhibited excellent visible-light-driven photocatalytic efficiency, which was increased to nearly 20 times than that of the products prepared by traditional solid-state reaction (SSR) and the nitrogen doped TiO2 (N-TiO2). Moreover, the photocatalyst could settle immediately, which is beneficial for the separation and recycle considering their future applications in waste water treatment.