Erbium-doped tellurite-based glasses with compositions of TeO2-ZnO-Na2O(TZN)and TeO2-ZnO-La2O3(TZL)are prepared, and fluorescence properties of Er3+:4I13/2→4I15/2 transition have been investigated as a function of erbium-doping concentration. It is found that fluorescence intensity decreases evidently with increasing erbium-doping concentration under higher doping, and it is mainly a result of concentration quenching effect in which energy migration takes place due to energy transfer via cooperative upconversion between Er3+ ions when the procedure of removing OH-1 by bubbling oxygen is adopted in melting glass. By fitting the rate equations of population to the normalised fluorescence decay curves, the coefficients of cooperative upconversion are obtained, and the values for the 4I13/2 are estimated to be CTZN=3.27×10-18cm3/s and CTZL=3.01×10-18cm3/s, respectively. Also, the critical concentration and the critical interaction distance are calculated, and the values for the TZN and TZL glasses are QTZN=11.2×1020　cm-3 and QTZL=11.8×1020cm-3, RTZN=0.597nm and RTZL=0.587nm, respectively. Compared with some other glasses reported, the tellurite glass prepared by us has a better rare-earth Er3+ ion solubility and a lower rate of energy transfer via cooperative upconversion, and may serve as good glass host for broadband fiber amplifiers.