A hierarchical flower-like SrTiO3 nanostructure was synthesized by a simple and direct hydrothermal method. The products were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Structure characterizations suggest that the as-synthesized SrTiO3 crystal has eight symmetric branches growing along the 〈111〉 direction and each branch has many ordered small laminae, forming a well-defined flower-like structure. By adjusting the pH value of the reaction system, the morphology could be changed continuously from flower-like structure to cube, then to sphere. The hierarchical flower-like SrTiO3 nanostructure exhibits a higher photocatalytic activity for degrading Rhodamine B than its cubic and spherical counterparts.