Abstract: In order to accurately evaluate the stealth performance of infrared materials and coating, the IRS400 type material emissivity measurement equipment was developed . It is mainly used in the temperature range of 50 ℃～400 ℃, spectrum range of 3 m～5 m and 8 m～12 m directional measurement for the emissivity of solid opaque material and coating sample. The importance of the material emissivity measurement for infrared stealth technology was introduced, the IRS400 type emissivity measurement equipment was described, including the technology performance and working principle. The IRS400 optic system adopted total reflection design, the detector selected the LiTaO3 pyroelectric detector, and the 50 ℃～1 000 ℃ black body radiation source standard device was utilized to calibrate the black body emissivity B（1,2）.By solving the key technology of calibration and environmental temperature compensation, the emissivity measurement uncertainty can be ensured less than 2%.