Aluminum nitride (AlN) nanowires have been studied extensively by scholars due to their excellent thermal conductivity. Aluminum nitride nanowires were prepared by direct nitriding method using melamine and yttrium fluoride as additives. The crystal structure and microscopic morphology of the reaction product were carried out by X-ray diffraction (XRD), scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM) and energy spectrometer (EDS). The promoting effects of melamine and yttrium fluoride on nitriding reaction were analyzed. The effects of different melamine content and different reaction temperatures were studied on the preparation of aluminum nitride nanowires. The results show that the addition of melamine increases the nitridation reaction rate and promotes the formation of nanowires. When the reaction temperature is 1 200 ℃, the mass ratio of aluminum powder to melamine is 1∶4, and the content of yttrium fluoride is 5% (mass fraction), aluminum nitride nanowires with high aspect ratio are successfully prepared.