Abstract: The automatic highprecision system, which is composed of temperature control system,precision goniometer system, optical system and electrical control system for measuring the temperature coefficient of refractive index of infrared materials is introduced in the paper. The temperature coefficient of refractive index is measured with the improved autocollimating method. The key index of the instrument is as follows: its wavelength range is 2～12μm,temperature range is -50～150℃,uncertainty is 3%. The instrument can meet the measurement requirement of temperature coefficient of refractive index of the different infrared materials. With this instrument, the temperature coefficient of germanium material has been measured and the results has been reported.