(100-x)(80GeS2-20Ga2S3)-xKI(x=0,10,20 mol%) chalcohalide glasses are prepared by traditional melt-quenching method.The differential thermal analysis(DTA),visible/near-infrared absorption spectroscopy,infrared transmission spectra are adopt to the analysis of the relationships of the composition,structure and properties of the GeS2-Ga2S3-KI ternary glass system.The results show that:the glass-forming regions of GeS2-Ga2S3-KI ternary system glasses are fairly big.When the content of KI is 10 mol%,the glass is of the best thermal stability.With the addition of KI,there has been no significant change in infrared cut-off wavelength of the glasses which are all 12.5 μm.While with the local field potentials increasing,the short-wave absorption of the glasses shifts to the shorter wavelength and the optical band gap increases.