Series of GeS2-Ga2S3-KCl chalcohalide glasses were prepared by traditional melt-quenching method. Thickness,density,refractive index,visible/near-infrared absorption and infrared transmission spectra were adopted to the analysis of the allowed direct interband optical transitions of optic gap with Tauc equation. The results show a good physical performance as it possesses a wide glass-forming regions of GeS2-Ga2S3-KCl pseudo-ternary glass system. With the increasing of KCl content,there were significant decreases in glass density and refractive index,but there is a significant augmentation of optic band gap. Others,some corresponding changes of glass host structure were deduced from FTIR and Raman spectra,as that the IR optic spectra was improved,just like the Raman spectrum changed by steps,IR absorption cutting-off edge red-shifted with regular. Based on the analysis of KCl adding in the glass host,a quantitative description was given about the correlations between IR multi-phonon absorption and fundamental phonon-vibration,as it shows a deterministic dependence of the optic optical properties of chalco-halide glasses on glass host.