Special nanostructures of porous anodic alumina (PAA), such as the petal-like micropattern and nanofibers of alumina, cannot be explained by the classical field-assisted dissolution and dynamic equilibrium models. Here, by combination of oxygen bubble mould and plastic flow model, a reasonable explanation for these special nanostructures is proposed. The petal-like micropatterns of PAA and nanofibers of alumina are all clarified by the oxygen bubble mould and the plastic flow model. The self ordering nanochannels of PAA are attributed to the oxide plastic flow around a gas bubble mould at each pore bottom. The petal-like micropatterns and nanofibers of alumina are attributed to chemical corrosion enhanced by the micro-gas-flow and micro-liquid-flow. (C) 2017 Elsevier Ltd. All rights reserved.