Abstract Ga 3+ -doped Eu 2 (MoO 4 ) 3 films were prepared by electron beam evaporation and annealed at 400 °C–800 °C in oxidizing atmosphere, and the relationship between Ga 3+ concentration and luminescence properties of the films was explored combining the characterization methods of XRD, excitation, emission spectra and decay curves. It was found that intensity ratio I ( 5 D 0 – 7 F 2 )/ I ( 5 D 0 – 7 F 1 ) was extremely susceptible to Ga 3+ concentration, and the luminescence intensity was significantly influenced by the doping of Ga 3+ . The intensity increased with Ga 3+ concentration ranging from 0 to 0.65 mol and reached a maximum at 0.3 mol and decreased when exceeding 0.65 mol. Finally, the effect of annealing temperature on photoluminescence was also obtained.