In this paper, the photocatalytic activity of the immobilized ZnO/Bi2O3 composite was effectively improved by a special composite technology and surface modification method. The ZnO thin film was coated by a connected Bi2O3 microgrid via a microsphere lithography strategy to form ZnO film/Bi2O3 microgrid heterojunction, which showed higher photocatalytic activity than the pure ZnO film, Bi2O3 film and ZnO film/Bi2O3 film composite under xenon lamp irradiation. The annealing temperature was determined to have a great effect on the photocatalytic activity of ZnO film/Bi2O3 microgrid heterojunction, and the optimum calcining temperature was determined to be 300 degrees C. Ag particles were deposited on the surface of the samples to further improve the photocatalytic performance. The relationship of the energetic positions of Ag with ZnO or Bi2O3 deduces the separation of photo-generated electrons and holes. (C) 2011 Elsevier B.V. All rights reserved.