Sm2O3-doped SrO-BaO-P2O5-B2O3 glass was prepared by a conventional melt quenching method in air. The glass was irradiated using X-rays to reduce the Sm3+ ions to Sm2+ ions. After the X-ray irradiation, photoluminescence studies at different temperatures showed that the conversion of Sm3+ to Sm2+ could be realized in this alkaline earth borophosphate glass. The luminescence of the Sm2+ ions showed a strong dependence on temperature. Photo-stability of Sm2+ ion was evaluated using a photo-bleaching method. Thermo-luminescence and life-time measurements were also investigated. The results of this study could be useful for understanding the reduction mechanism of Sm3+ ions to Sm2+ ions in alkaline earth borophosphate glass.