We employ plane-wave with ultrasoft pseudopotential method to calculate and compare the total density of states and partial density of states of bulk-phase GaN,Ga0.9375 N,and GaN0.9375 systems based on the first-principle density-functional theory(DFT).For Ga and N vacancies,the electronic structures of their neighbor and next-neighbor atoms change partially.The Ga0.9375 N system has n-type semiconductor conductive properties,whereas the GaN0.9375 system has p-type semiconductor conductive properties.By studying the optical properties,the influence of Ga and N vacancy defects on the optical properties of GaN has been shown as mainly in the low-energy area and very weak in high-energy area.The dielectric peak influenced by vacancy defects expands to the visible light area,which greatly increases the electronic transition in visible light area. We employ plane-wave with ultrasoft pseudopotential method to calculate and compare the total density of states and partial density of states of bulk-phase GaN, Ga 0.9375 N, and GaN 0.9375 systems based on the first-principle density-functional theory ( DFT). For Ga and N vacancies, the electronic structures of their neighbor and next-neighbor atoms change partially. The Ga 0.9375 N system has n-type semiconductor conductive properties, and the the GaN 0.9375 system has p-type semiconductor conductive properties .By studying the optical properties, the influence of Ga and N vacancy defects on the optical properties of GaN has been shown as mainly in the low-energy area and very weak in high-energy area. The dielectric peak influenced by vacancy injury expands to the visible light area, which greatly increases the electronic transition in visible light area.