β-Ga2O3∶Eu3+ samples with different fluence were prepared by ion implantation method and then annealed in air where Eu3+ optical activation was successfully achieved. The stress variation trend of β-Ga2O3 single crystals with Eu3+ fluence was characterized by Raman spectra and X-ray diffraction. It was found that with the increase of Eu3+ fluence, the crystal lattice stress increases first and then decreases, and its internal mechanism was analyzed. The luminescence properties of Eu3+ were characterized by cathodoluminescence spectra. The wide defect luminescence peak near 380 nm and the characteristic luminescence peaks of Eu3+ near 591 nm, 597 nm and 613 nm were observed. By Gaussian fitting, the 380 nm luminescence peak could be divided into three peaks located at about 360 nm, 398 nm and 442 nm, which are related to the self-trapping excitons and donor-acceptor pairs, respectively. In addition, the position and intensity of Eu3+ luminescence peaks were affected by the localized crystal field of the host.