Step-by-step change of growth temperature was investigated to control GaN nanorod diameter in the molecular-beam epitaxy, It was found that when the growth temperature is decreased, the GaN nanorod diameter gradually increases with the progress of lower temperature growth. On the contrary, opposite change of the diameter was observed when the growth temperature is increased during nanorod growth. The Ga adatom density on the GaN surface and the dissociation in the GaN nanorods play an important role on the shape variation of nanorods and we can control the diameter of GaN nanorods by regulating the growth temperature. (C) 2013 Elsevier B.V. All rights reserved.