Hierarchically structured Bi24O31Br10 photocatalysts were synthesized by a facile solvothermal method with the help of soluble starch. As-prepared samples were characterized by XRD, SEM, EDS, TEM, FTIR and N-2 adsorption. It was found that starch played a key role in shaping morphology of Bi24O31Br10, and especially a novel grain-like Bi24O31Br10 hierarchical architecture could be obtained by adding the right amount of starch. The forming mechanisms of different microstructures were proposed. The photocatalytic performances of the obtained samples were also investigated by degradation of Rhodarnine B (RhB) under visible light illumination. Starch-modulated Bi24O31Br10 photocatalysts exhibited obviously enhanced photocatalytic activity, whose mechanism was discussed. The present work demonstrated a novel strategy to modulate the structures, morphologies and properties of materials, which can be extended to other photocatalysts. (C) 2016 Elsevier Ltd. All rights reserved.