The 15 μm emission spectrum corresponding to the 4I13/2→4I15/2 transition and upconversion of Er3+ in tellurite glass in the temperature range from 8 to 300K is studied. The emission spectrum of Er3+: 4I13/2→4I15/2 transition is also analyzed using a peak-fit routine, and an equivalent four-level system is proposed to estimate the Stark splitting for the 4I15/2 and 4I13/2 levels of Er3+ in the tellurite glass. The results indicate that the 4I13/2→4I15/2 emission of Er3+ has considerable broadening due to a significant enhancement of the a' and b' emission peaks. Temperature-dependent FWHM are investigated, the results show that a monotonic increase of FWHM is observed for temperatures from 8 to 300K. Intense upconversion emission signals around 529, 545 and 669nm corresponding to the 2H11/2, 4S3/2, and 4F9/2 transitions, respectively, to the 4I15/2 ground state are generated and are measured as functions of temperature in the 8 to 300K range. The most remarkable result is observed in the green upconversion signal around 546 and 669nm which presented a maximum intensity enhancement of 2198 and 1556 times around 80K compared with that around 300K. Monotonic decrease is observed at temperatures above 80K. In the same temperature range the signal at 529nm diminishes to zero with lowering temperature.