Abstract: In order to meet the spectral emissivity test and evaluation of infrared materials, a directional spectral emissivity measurement apparatus based on a solid material emissivity testing model was developed. Solid materials can be measured in the temperature range of 50℃ to 300℃ and in the spectral range of 1.3m to 14.5m. Some experiments were done under different conditions, spectral emissivity graphs were given. Final errors caused by the difference between sample surface temperature and blackbody cavity temperature were analyzed and error graphs changing with temperature and wavelength were shown when temperature differences were 1℃ and 2℃.