Abstract We fabricated a series of (In2O3)0.75(Ga2O3)0.1(ZnO)0.15 thin films using the pulsed laser deposition (PLD) method at room temperature under same oxygen pressure, and annealed these films at different temperatures from RT to 300 °C under vacuum. The effect of thermal annealing on the properties of In–Ga–Zn–O (IGZO) films was studied. The structural, optical and electrical properties of the films were measured by various diagnosis tools. Surface morphology of all IGZO thin films was examined by Atomic Force Microscopy (AFM). X-ray diffraction (XRD) patterns showed that the mixed crystalline and amorphous phases appear in the as-grown film and in the films annealed temperatures from 100 °C to 300 °C. The maximum carrier mobility was 32 cm2/(V s) in the film annealed at 300 °C. The transmission spectrum of film annealed at 300 °C shows the better light transmission and narrower band gap. The IGZO thin films with high mobility and transparency are highly desirable for the fabrication of flat panel display devices.