Pr, Er, Tm co-doped GaN thin films were prepared via ion implantation. After thermal annealing treatment, 300 K and 80 K cathodoluminescence spectra were measured to investigate the luminescent properties. To our knowledge, this is the first observation of Pr, Er, and Tm simultaneous emissions in one GaN thin film. In addition, comparative studies have been carried out on the cathodoluminescence properties of Tm-implanted GaN with Tm and Er co-implanted GaN. The energy transfer process between Tm and Er ions was discussed. (C) 2017 Elsevier B.V. All rights reserved.