Without template, three-dimensional nanowall ZnO films were synthesized in an atmospheric pressure chemical vapor deposition (APCVD) system by adjusting zinc species concentration. In the high ordered film, the vertical nanosheets were assembled along three directions angled approximately 120 degrees. The extremely strong ZnO (0 0 0 2) peaks in X-ray diffraction patterns testified the preferred (0 0 0 1) orientation and high crystalline quality of the films. The low transmittances of nanowall films were attributed to the strong inner reflection and scattering. These results show that the simplified APCVD method is potential in synthesizing uniform nanowall ZnO films. Crown Copyright (c) 2012 Published by Elsevier B.V. All rights reserved.