The function characteristics, main indicators, working principle and typical system compositions of the spaceborne microwave radiometer are briefly introduced. The development level and application status of current domestic and foreign spaceborne terahertz band polarization grid, frequency selective surface, feed horn, receiver front-end etc, are highlighted by combining with the key components of quasi-optical feed system and receiver, as well as the application requirements on key performance specifications such as sensitivity. The gaps between key specifications are compared. The technical difficulties in product design and development of terahertz frequency are analyzed. In view of the development demand of spaceborne microwave radiometer of China, the development trend and application demand of key terahertz components are prospected, providing reference for the development of spaceborne passive remote sensing in China.