The spectral responsivity of Fourier Transform Infrared Spectrometer (FTIR) measurement system of high temperature blackbody infrared radiation characteristics is calibrated via ThermoGage HT9500 high temperature reference blackbody furnace from National Institute of Metrology, China (NIM). A calculation model of the spectral responsivity calibration of FTIR measurement system is established. The infrared spectrum of the blackbody radiation source is measured in the temperature range from 1273 K and 1973 K on the wavelength range from 1 μm to 14 μm. Calibration is carried out within the temperature range from 1373 K to 1873 K on the wavelength range between 1 μm and 13 μm. The infrared spectral radiation characteristics of ThermoGage HT9500 high temperature reference blackbody furnace are represented. The results indicated that the method of piecewise linear calibration was practicable. The measured infrared spectrum in the temperature range from 1373 K to 1873 K on the wavelength range between 1 μm and 13 μm was compared with the calculation which showed the signal divergence less than 1%. And the calculated temperature obtained by inverse calculation in this temperature region was compared with the actual temperature which showed the temperature divergence less than 0.45%.