Abstract: Proton transportation process was simulated with the energy from 50 keV to 3 MeV in GaN by using Monte-Carlo method. The distributions of incident ions and irradiation induced vacancies were obtained. It is obvious that the proton beams enlarge horizontally when incidence energy is less than 300 keV and all the incidence ions are stopped in the material at 3.5 μm thickness of GaN. The transverse extending of proton beam decreases and the penetration probability increases with incidence energy. Almost all of incidence ions pass through the material when energy is higher than 500 keV. The distribution and defect type induced by different energy of proton are different in the material of GaN.