Semiconducting nanowires offer the possibility of nearly unlimited complex bottom-up design, which allows for new device concepts. However, essential parameters that determine the electronic quality of the wires, and which have not been controlled yet for the III–V compound semiconductors, are the wire crystal structure and the stacking fault density. In this paper, we have used the molecular dynamics simulations to study the formation of the stacking faults in GaN NW along  and [11-20] directions. The results show that under same growth condition the GaN NW along  has stacking fault while there is no stacking fault in GaN NW along [11-20]. We have analysis the possible reason and further study is underway.