Abstract: The radiometric temperature and other key technical indicators of space infrared payloads directly determine their on-orbit target recognition capability. Therefore, in all ground development stages such as design and testing, it is imperative to conduct space environment simulation tests. By accurately calibrating these indicator parameters, measurement errors caused by environmental differences can be eliminated, thus ensuring the on-orbit detection performance of the payloads. To meet the demand for ground simulated radiometric calibration of space infrared payloads and guarantee their stable on-orbit operation, this paper has developed a dedicated low-temperature radiometric temperature calibration device for space infrared payloads. The device takes a high-emissivity standard blackbody radiation source, an infrared standard radiometer and a low-temperature collimator subsystem as its core components, and is entirely arranged in a vacuum chamber. Relying on liquid nitrogen cycle refrigeration technology, it accurately simulates the real low-temperature and vacuum working environment of space. During the calibration process, the high-emissivity standard blackbody serves as the core radiation source to provide stable infrared radiation for the calibrated payloads. After the infrared standard radiometer completes the calibration of the temperature difference output of the target blackbody and background blackbody in the low-temperature collimator subsystem, the device successfully achieves accurate calibration of core parameters such as radiometric temperature, MRTD and NETD of space infrared payloads in the long-wave infrared band. It effectively provides authoritative support for traceability of quantity values, correction of system errors and verification of reliability for the performance indicators of the payloads under low-temperature operating conditions.