Abstract: SiGe single crystals with different concentrations of doping Ge in CZSi were measured by Fourier transform infrared spectroscopy （FTIR） at 300 K and 10 K. The results indicate that new peaks appear at wave number of 1118 cm^-1, 710 cm^-1 and 800 cm^-1. The new peaks of the spectroscopybecome clearer with increasement of Ge. The absorption peak of carbon shifts to low frequency side with increasement of Ge. The crystal data and structure refinement are obtained by single-crystalX-ray diffraction. The lattice constant of SiGe （Ge:10wt%） is 0.5446nm.