Bulk glasses have been prepared in the TeO 2 –ZnO–ZnCl 2 systems. Their characteristic temperatures were determined and analyzed. Raman and FT–IR spectra were used to analyze the effect of ZnCl 2 on the structure and spectral properties of tellurite glasses and OH − groups in this glass system. The spectroscopic properties including absorption spectra, emission cross-sections and fluorescence lifetimes of Yb 3+ in TeO 2 –ZnO–ZnCl 2 were measured and calculated. It is demonstrated that the progressive replacement less than 20 mol% of TeO 2 by ZnCl 2 improves the thermal stability, removes the OH − groups, turns TeO 4 bi-pyramidal arrangement into TeO 3 (and/or TeO 3+1 ) trigonal pyramids structures and results in the decrease of the symmetry of the structure, which increases the emission cross-sections and lifetimes. But when the content of ZnCl 2 up to 30 mol%, the glass system becomes more hygroscopic and introduces more OH − groups, which decrease the emission cross-sections and shorten the lifetimes. The results show that the glass system with 69TeO 2 –10ZnO–20ZnCl 2 –1Yb 2 O 3 is a desirable component for active laser media for high power generation.