Ordered crystalline GaN nanowires embedded in the nanochannels of anodic alumina membrane (AAM) were achieved by direct reaction Ga with NH3. The impact of reaction temperatures on Raman spectroscopic properties of GaN nanowires is investigated. X-ray diffraction and transmission electron microscopy (TEM) observations demonstrate that the crystalline GaN nanowires have hexagonal wurtzite structure. The hexagonal wurtzite structure GaN nanowires prepared at 960 degreesC are about 40 nm in diameter and up to several hundreds of micrometers in length.