Erbium-doped TeO2-based oxysulfide glasses have been prepared in argon atmosphere in graphite crucibles. The results of thermal analysis and spectroscopic properties of Er3+ have been studied in terms of sulfide influence. As a function of composition, we have measured principally the optical absorption, spontaneous emission, and lifetime of the materials. Judd-Ofelt theory was introduced to calculate bandwidth and emission cross-section of Er3+. The results demonstrate that addition of sulfide in tellurite glasses results in broad emission spectra, with high emission cross-section, slightly low emission lifetime and a comparatively high thermal stability as pure oxide glasses.