A serial of chalcogenide glasses based on 78GeS2-12Ga2S3-10CsI (in molar%) system doped with the different radios of Ho3+/Tm3+ ions were synthesized by melt-quenching method.Their absorption spectra and mid-infrared fluorescence under 808 nm laser excitation were measured.According to Judd-Ofelt theory, the intensity parameters Ωi(i=2, 4, 6), spontaneous transition probabilities Arad and radiative lifetomes τr for Ho3+ ion were calculated.Absorption cross-sections σa, emission cross-sections σe and gain coefficient G(λ) corresponding to the emission of Ho3+ ions at 2.0 μm were obtained.By changing the Tm3+ concentration, the energy transfer regime of Tm3+ and Ho3+ ions under 808 nm excitation was investigated.The results show that Ho3+/Tm3+-codoped Ge-Ga-S-CsI glasses would be a potential material for 2.0 μm emission.