Ag/tetrapod-like ZnO whisker (T-ZnOw) nanocompounds were successfully synthesized using photodeposition method. Remarkable improvements in photocatalytic property for all the nanocompounds are observed, while the extents of the improvements increase with increasing polyethylene glycol (PEG) contents. Various tests were carried out to determine the mechanism for the greatly improved photocatalytic property. And it is found that PEG can reduce Ag+ into Ag under UV irradiation, which can be subsequently deposited on the surface of T-ZnOw as nanoparticles. The conclusion that the heterostructure of Ag/T-ZnOw nanocompound contributes to its greatly enhanced photocatalytic property is proposed and later validated by carefully discussing the photocatalytic mechanism. (C) 2011 Elsevier B. V. All rights reserved.