With the development of infrared optics, low-loss waveguide materials are required. Especially, low-loss optical fiber development for far-infrared application has become a focus. Chalcogenide Ge-As-Se-Te(GAST) glasses and fibers for far-infrared light are prepared and investigated in this paper. The thermal properties and the infrared transmissions are reported. The influences of oxygen and hydrogen on the glass transmission and fiber attenuation are discussed. Low-loss GAST fiber with a structure of fine core/cladding is reported by a novel extrusion method (0.46 dB/m at 8.7 m, 1.31 dB/m at 10.6 m, base loss being under 1 dB/m from 7.2 to 10.3 m). Here, the glasses are prepared by traditional vacuum melt-quenching and vapor distillation method. Structure and physical properties of GAST glass system are studied with X ray diffractions and thermal expansion instrument. Optical spectra of GAST glass system are obtained by spectrophotometer and infrared spectrometer. Main purification processes with different oxygen-getters (magnesium and aluminum) are disclosed. The fiber attenuation is measured by the cut-back method with an Fourier transform infrared spectroscopy spectrometer. The lowest loss of this fiber can be reduced to 1.32 dB/m at 10.6 m, as it has a structure of Ge20As20Se15Te45 core and Ge20As20Se17Te43 cladding. The results show that these glasses are well transparent in a wide infrared window from 1.1 to 22 m, and these glass fibers can transmit far-infrared light up to 12 m, thus the GAST glass system is one of good candidates for far-infrared transparent materials. The fiber attenuation can be reduced effectively by the reasonable purification and novel extruded-processing. These fibers are suited for the power delivery of CO2 laser.