Deep level transient spectroscopy measurements were used to characterize the ele ctrical properties of metal organic chemical vapor deposition grown undoped, Er- implanted and Pr-implanted GaN films. Only one deep level located at 0.270 eV be low the conduction band was found in the as-grown GaN films. But four defect le vels located at 0.300 eV, 0.188 eV, 0.600 eV and 0.410 eV below the conduction b and were found in the Er-implanted GaN films after annealing at 900 ℃ for 30 mi n, and four defect levels located at 0.280 eV, 0.190 eV, 0.610 eV and 0.390 eV b elow the conduction band were found in the Pr-implanted GaN films after annealin g at 1050 ℃ for 30min. The origins of the deep defect levels are discussed. Aft er annealing at 900℃ for 30min in a nitrogen flow, Er-related 1538nm luminescen ce peaks could be observed for the Er-implanted GaN sample. The energy-transfer and luminescence mechanism of the Er-implanted GaN film are described.