Abstract: The hot calibration target is used as a space microwave radiometric brightness temperature measurement standard for real-time calibration of microwave detection payloads in remote sensing satellites, providing high-precision and high-stability standard radiation brightness temperature signals. It is an important component of the satellite. The radiation calibration and standard transfer of space microwave detection payloads are based on the blackbody radiation source method, which is the most widely used method at present. Currently, the space microwave radiometers carried by the world’s three major polar orbit meteorological satellites NOAA（USA）, MetOp（Europe）, FY（China） all use the microwave blackbody radiation source method as the reference for on-board hot radiation brightness. In response to the on-orbit calibration application requirement of the FY-3 meteorological satellite MWTS and MWRI, this research adopts a coated periodic tetrahedral pyramidal array structure for calibration blackbodies. By integrating comprehensive electromagnetic and thermal performance design, precision manufacturing technologies for blackbodies and coatings, as well as high-precision temperature measurement and control techniques, the project has overcome the engineering challenges in developing spaceborne thermal calibration sources featuring broadband, high microwave emissivity and superior temperature uniformity. Its core technical specifications cover an operating frequency range of 10.65 GHz to 191.31 GHz, with a microwave emissivity of 0.999, the temperature non-uniformity of 0.10 K, and the temperature measurement accuracy of 0.05 K. The first domestically developed space-borne microwave hot-calibration target has been realized, achieving full localization. It has been successfully applied to the FY-3 satellite MWTS and MWRI from batch 01 to 03, ensuring the autonomy and independence of China’s space microwave radiometer calibration payload. The core guarantee of space measurement has been established for the quantitative application of the FY-3 meteorological satellite in China.