The N-doped β-Ga2O3 films were grown on Si and quartz substrates by RF magnetron sputtering in different ammonia partial pressure ratios (from 0% to 30%). The influence of ammonia partial pressure ratio and annealing treatment on the optical and structural properties were studied. The microstructure, optical transmittance, optical absorption and optical energy gap of the N-doped β-Ga2O3 films were significantly changed with the increasing of ammonia partial pressure. The green, blue and ultraviolet emission bands were observed and discussed.