In order to output the ideal infrared fluorescence matrix glass, a serial of chalcogenide glasses based on Ge-Ga-S-KBr system doped with different Er3+ concentrations are synthesized by a melt-quenching technique. The refractive indexes, absorption spectra, mid-infrared emission spectra of samples are measured. The oscillator strengths of absorption lines of Er3+ ions are calculated using the absorption spectra. The intensity parameters (Ωi,i=2,4,6), transition probabilities (A), branching ratios (β) are predicted for Er3+ ions in the samples using the Judd-Ofelt theory. The mid-infrared emission properties are investigated for the samples with the different Er3+ concentrations under 808 nm laser excitation. The 2.8 μm-emission cross-section is calculated using the theory of the Futchbauer- Ladenburg. The results indicate that the fluorescence under 808 nm excitation with peak wavelength at 2.8 μm is due to the Er3+∶4I11/2→4I13/2 transition. The intensity of the mid-infrared fluorescence is enhanced by increasing the concentration of the Er3+ from 0.4 wt% to 1.0 wt%. Multiphonon relaxation rate is estimated to be 37 s-1 for the Er3+∶4I11/2 level.