A room-temperature photochemical method was introduced to fabricate SnO2-reduced graphene oxide (SnO2-rGO) composite with a new type of structure. SnO2 dense layers were directly grown on the two sides of an rGO sheet through ultraviolet light (UV) irradiation of a mixed precursor solution of SnSO4, H2SO4, and graphene oxide for 6h. The composite possessed a novel flat flake-like structure consisting of two SnO2 dense layers and an rGO sheet sandwiched in between. In contrast to most graphene-based composites, the fabricated composite was non-flexible, wrinkle-free and rGO surfaces were completely covered. The composite could be used in photocatalysis and exhibited remarkably enhanced activity in degradation of p-nitrophenol under low intensity of UV light or sunlight. The activity was more than 12 times that of pure SnO2 and considerably higher than that of other SnO2-rGO composites. The dense layer immobilized the flat structure, promoted the photocatalytic activity, and maintained the long-term stability of the composite. After preservation of more than 12 months in ambient condition, the composite showed a nearly constant activity. This photochemical method can be used to fabricate graphene-based composites with regular structure, high performance, and long-term stability. (C) 2017 Elsevier B.V. All rights reserved.