Abstract: To accurately evaluate the thermal radiation properties of thermal control materials in spacecraft cryogenic environments, two emissivity measurement systems were developed: a hemispherical emissivity measurement system based on the steady-state method, and a spectral emissivity measurement system based on the energy method. The former enables broadband hemispherical emissivity measurements from 60 to 300 K, while the latter enables spectral emissivity measurements in the mid- to far-infrared range (8–200 μm) at 30–300 K. Tests were conducted on white paint coatings and flexible thermal control films. Results indicate significant temperature dependence, with the hemispherical emissivity of the white paint coating increasing from 0.48 to 0.90 between 60 K and 220 K. Both systems demonstrate a combined standard uncertainty below 5%, providing reliable data to support the evaluation and thermal design of spacecraft thermal control materials.