A series of (100-x)(GeTe4)-xGa (x=0, 5, 10 mol%) far infrared transmitting chalcogenide glasses is prepared by the traditional melt-quenching method. In this paper, the differential thermal analysis (DTA), visible/near-infrared absorption spectroscopy, infrared transmission spectra are adopted to analyze composition, structure and performance of the GeTe4 glass system with the addition of Ga. The results show that the Te-Ga bond is formed, which can reduce Te metallic character. When the content of Ga is 10 mol%, the glass is of the best thermal stability. With the addition of Ga, the transmission percentage is improved and infrared cut-off wavelength of the glasses extends beyond 20 μm. Based on the metallization criterion and average bond energy, the relationship between optical band gap and composition is investigated.