This article reported a well-organized 3D urchin-like hierarchical TiO2 which was synthesized by a simple solvothermal method without using any template or surfactant. The results of scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and powder X-ray diffraction showed that the hierarchical morphology and size of TiO2 could be effectively controlled by adjusting the precursor ratio of tetrabutyl titanate to TiCl4 solution, the concentration of TiCl4 solution, the solvothermal temperature, and the reaction time. It is believed that the formation of the urchin-like hierarchical TiO2 followed a 'nucleation-self-assembly-dissolution-recrystallization' growth mechanism. In addition, the excellent photocatalytic activity of the urchin-like hierarchical TiO2 was confirmed by photodegradation of methyl blue in water.