Three-dimensional SnO2/α-Fe2O3 semiconductor hierarchical nanoheterostructures were synthesized for photocatalysis through a low-cost and environmentally friendly hydrothermal strategy, by crystallographic-oriented epitaxial growth of SnO2 on three-dimensional α-Fe2O3 flowerlike hierarchical nanostructures. In this photocatalyst, visible-light-active Fe2O3 flowerlike hierarchical nanostructures were used as a medium to absorb photons and convert them into photogenerated charges, and SnO2 nanoparticles were used as charge collectors to transport the photogenerated charges. The SnO2/α-Fe2O3 semiconductor hierarchical nanoheterostructures exhibited excellent visible-light photocatalytic ability for the degradation of methylene blue; this was attributed to the large specific surface area, wide visible-light absorption range, and efficient electron–hole pair separation properties of the SnO2/α-Fe2O3 nanoheterostructures. The SnO2/α-Fe2O3 material showed improved separation of photogenerated electron–hole pairs owing to the potential-energy differences between SnO2 and α-Fe2O3, and therefore exhibited enhanced photocatalytic activity. This paper highlights the SnO2/α-Fe2O3 semiconductor hierarchical nanoheterostructures as potentially more environmentally friendly materials for use in organic pollutant degradation for environmental pollution cleanup operations.