Er3+-doped 53ZrF4-20BaF2-4LaF3-3AlF3-20NaF-2.4PbF2 (ZBLAN) fluoride transparent glasses are prepared by the melt quenching method. The fluorescence spectra are measured for the transition of Er3+ Stark sublevels 4S3/2(1)→4I15/2 and 4S3/2(2)→4I15/2 (λ1=542 nm, λ2=548 nm) with in the temperature range of 10 K~540 K. The results show a rapid decrease in emission intensity and an obvious difference in decay rate with the temperature increase. According to the configurational coordinate, the mechanism is proposed to involve the difference of thermal quenching rate from the fitted activation energy (ΔE) of 0.078 eV and 0.049 eV for two sublevels of 4S3/2(1) and 4S3/2(2), respectively. The calculated fluorescence intensity ratio (FIR), which is corresponding to the transition of Er3+ stark sublevels 4S3/2(1)→4I15/2 and 4S3/2(2)→4I15/2, shows a linearly increase with temperature rise and then tends to flatten at high temperature region. The temperature sensitivity of sample is obtained for the maximum value of 0.0011 K-1 at the temperature of 90 K. The features in temperature sensitivity would be an application of optical temperature sensor.