By measuring the emission spectra and the fluorescence lifetime of the 4 I 13 /2 state of Er 3+ ions in Gd 2 SiO 5 crystal at different temperatures,the effects of temperature on the spectra and the lifetime of the 4 I 13 /2 state are investigated. When the temperature increases,the emission line width for the 4 I 13 /2 → 4 I 15 /2 transition is broadened,and the main emission lines at 1 596,1 609,and 1 644 nm shifte toward shorter wavelengths. The measured lifetime of the 4 I 13 /2 state decreases from 13.2 to 8.4 ms with temperature increase from 13 to 300 K,which is mainly due to the temperature dependence of multiphonon relaxation between the 4 I 13 /2 and 4 I 15 /2 states and the changing population distribution among the Stark levels within the 4 I 13 /2 state. The experimental results imply that low temperature condition is better for the ～1.6-μm laser output. By measuring the emission spectra and the fluorescence lifetime of 4 I 13/2 state of Er 3+ ions in Gd 2 SiO 5 crystal at different temperatures, the effects of temperature on the spectra and the lifetime of the 4 I 13/2 state are investigated. When the temperature increases, the emission line width for the 4 I 13/2 → 4 I 15/2 transition is broadened, and the main emission lines at 1 596,1 609, and 1 644 nm shifte toward shorter wavelengths. The measured lifetime of the 4 I 13/2 state decreases from 13.2 to 8.4 ms with the temperature increase from 13 to 300 K, which is mainly due to the temperature dependence of multiphonon relaxation between the 4 I 13/2 and 4 I 15/2 states and the changing population distribution among the Stark levels within the 4 I 13/2 state. The experimental results imply that low temperature conditions is better for the ~ 1.6-μm laser output.