A series of new 70TeO₂－(15－x)B₂O₃－xNb₂O₅－15ZnO－1 wt%Er₂O₃(TBN x=0,3,6,9,12,15 mol%)tellurite glasses were prepared. The thermal stability and spectral properties,such as absorption spectra and emission spectra of the glass samples were measured and investigated. Three intensity parameters Ω_t(t= 2,4,6)(Ω₂=(5.42～6.76)×10^－20cm²,Ω₄=(1.37～1.73)×10^－20cm²,Ω₆=(0.70～0.94)×10^－20cm²)of Er³⁺ were calculated by Judd-Ofelt theory. It was found that the intensity parameters Ω_t(t=2,4,6)increase with the increasing of Nb₂O₅ content from 0 mol% to 6 mol% and then decrease. It indicates that the covalence between the Er³⁺ and O^2－ is mainly affected by the number of non-bridging oxygen ions. However,the effect of the electro negativity between negative ions and positive ions on the covalence between the Er³⁺ and O^2－ can be neglected. The stimulated emission cross-section(σ_e=(0.77～0.91)×10^－20cm²)of the Er³⁺ ions ⁴I_13/2→⁴I_15/2 transition were calculated according to the McCumber theory and the full width at half maximum(FWHM=65～73 nm)of the ⁴I_13/2→⁴I_15/2 emission were measured. The FWHM and emission cross-section of Er³⁺ ions in different glass hosts were compared. The results show that this tellurite glass has wider bandwidth and could be the promising host material for broadband amplification.