The general features in ion-irradiated GaN are identified as basal stacking faults and dislocation loops. Understanding the atomic configuration of those lattice defects are important to reduce implantation damage during ion doping in GaN devices. In this study, however, due to the poor understanding of the basic mechanisms involved in such a process, Wurtzite GaN film bombarded with 5 MeV Xe ions was studied by using Transmission electron microscopy (TEM) and high resolution TEM (HRTEM). Analyzing the microstructure by TEM, we show the formation of a high density of basal stacking faults, pyramidal dislocation loops and point defect clusters. These defects were carefully investigated by high resolution TEM (HRTEM), we notice the growth of basal stacking faults accompanied with the formation of pyramidal and prism dislocation loops. The most of observed stacking faults and dislocation loops are identified as gallium interstitials. This work is expected to provide insights into the understanding mechanisms controlling the irradiation damage of GaN exposed to ion irradiation and will benefit the fabrication of GaN devices.