1wt% Er3+-doped 75GeS2-15Ga2S3-10CsI(GGSI) chalcogenide glasses are fabricated and the properties of these glasses are investigated.The mode field distribution in mid-infrared(IR) region of the designed photonic crystal fiber(PCF) is worked out by the multipole method.Based on the rate equations and light propagation equations,the numerical simulations on mid-infrared gain versus the fiber length,pump power and signal power for the Er3+-doped GGSI chalcogenide glass PCF are presented in this paper,which are compared with those of conventional fiber amplifiers.Effects of energy transfer between Er3+ levels due to cross-relaxation and cooperative up-conversion are considered here.It is shown that the average signal gain of the Er3+-doped GGSI chalcogenide glass PCF exceeds 40 dB in the region of 2 750-2 950 nm,which presents a bigger signal mid-infrared gain than conventional fibers with 20 dB.