A new glass of Lu2O3-B2O3-SiO2-Na2O-Er2O3 system is prepared by the technique of high-temperature melting at different temperatures and the formation range of the glass is experimentally obtained. Effects of the B2O3 content on the infrared spectral properties such as the 1.5 μm emission bandwidth corresponding to 4I13/2→4I15/2 transition and the Judd-Ofelt parameter Ωt (t = 2, 4, 6) of Er3+ ions in the glass has been observed. The glass exhibits big integrated emission cross sections for the 1.5 μm emission band. Excellent thermal stability of the glass has been demonstrated using differential thermal analysis. The Er3+-doped lutetium borosilicate glass is a great candidate for broadband erbium doped fiber amplifiers.