A series of Cu-improved GeTe₄-Ga₂Te_{3chalcogenide} glasses were prepar ed by traditional melt-quenching method.In this paper,the X-ray diffraction (X RD) diffraction,scanning electron microscope (SEM),differential thermal analysis (DTA),spectrophotometer and infrared spectrometer are adopted to analyze the dependence of the composition on struct ure and optical properties of the glass samples.The Tauc equation is used to calculate the ind irect optical band gap.The results show that with the increasing of Cu content,both the density and the mo lar volume of the glasses decrease.A red-shift occurs in the short-wavelength absorption cut-off ed ge of the glasses,and the band gap is decreased.The maximum ΔT of 103℃ is ob taine d for the glass composition of (GeTe₄)₆₈(Ga₂Te₃)₂₆Cu₆. These prepared GeTe₄-Ga₂Te₃-Cu glasses all have wide optical transmissio n window and the infrared cut-off wavelength is far beyond 20μm,which implies that the studied far-infrared Te -based chalcogenide glasses have an important potential application.