THz atmospheric transmission measured at antarctic Dome A

China is planing to construct a 5-m THz telescope (DATE5) at Dome A, Antarctic, which is the best site on the earth for astronomical observations in the THz regime. To evaluate the atmospheric transmission at Dome A, we have developed a broadband Fourier transformer spectrometer for 0.75~15 THz (Dome A FTS). The details of the instrument and measurement results will be presented.