In this paper, we report that a silicon hierarchical structure, silicon nanoporous pillar array (Si-NPA), was prepared and its visible photocatalytic properties were studied by selecting methyl orange (MO) as the target substance. It was shown that a broadband visible light absorption beyond 96% was reached and a one-hour degradation of 97.7% was achieved under optimized conditions. The excellent photocatalytic property of Si-NPA was attributed to the enlarged bandgap brought by quantum confinement effect and the unique surface morphology and microstructure of Si-NPA. Our experiments might have put forward a promising route for fabricating Si-based photocatalyst to degrade organic pollutants in water. (C) 2017 Elsevier B.V. All rights reserved.