The diffusion behaviour of 1.0 and 2.0 MeV Au+ implanted into LiB3O5 single crystal has been studied by the Rutherford backscattering of 2.1 MeV He ions. Annealing was performed at temperatures of 600, 700, and 800℃each for 30min. The results show that the diffusion behaviour is quite different in two cases. In LiB3O5, the depth distribution of the 1.0 Me V Au is nearly Gaussian and becomes bimodal after annealing at 800℃ for 30 min.But in the case of 2.0 MeV, the depth distribution of as implanted Au+ in LiBsO5 has splitting behaviour. After 800C for 30 min annealing, there is no obvious diffusion observed. The precise interpretation is needed.