The general consideration and design ideas for an infrared horizontal Attenuation Total Reflection(ATR) instrument used in the Fourier transform spectroscopy were introduced

and the penetrating depth and reflective times affecting on the spectrum intensity were analyzed. The facula was reduced three times and focalized on samples

the optical system was restored and focalized to a receiver

and the energy usage ratio can be calculated and analyzed. Several samples were tested by the FTS-7 Fourier transform spectroscopy

the results show that the energy usage ratio is 5%

the total reflection is fifteen times

and the quality of the spectrum is close to the level of the similar instrument.