As a member of wide band gap semiconductor materials, β-Ga2O3 with stable structure has a wider band gap and higher Baligar value than SiC and GaN, which has attracted extensive attention of researchers in recent years. In this paper, β-Ga2O3 thin films were grown on C-plane sapphire substrates by RF magnetron sputtering, and the influence of the substrate heating temperature during the sputtering process was explored. After sputtering, the quality of gallium oxide thin films was improved by high temperature annealing treatment. The effect of substrate heating temperature and post-annealing temperature on the crystal structure and surface morphology of gallium oxide films were studied. The crystal structure and surface morphology of β-Ga2O3 thin films were characterized by X-ray diffraction(XRD) and atomic force microscopy(AFM). The experimental results show that with the increase of substrate heating temperature, the surface roughness of β-Ga2O3 film decreases gradually, and the crystal quality of the film is significantly improved. After annealing in oxygen atmosphere, the appropriate post-annealing temperature is conducive to recrystallization of gallium oxide thin film, increase the grain size, effectively repair the surface state and point defects of the thin film, and improve the crystal quality of the film obvious advantages.