Abstract: The active phased array antenna is more and more widely used in the space-borne radar. As the core part of the active phased array antenna, the T/R module directly affects the performance of active phased array antenna. Packaging can provide a good work environment for electronic components and circuits of micro-assembly T/R module. For requirements of high power, high integration, high reliability and so on, packaging design technology has become one of the key technologies for designing micro-assembly T/R module. Based on the application requirements of packaging in micro-assembly T/R module of space-borne radar, the basic composition of a T/R module is introduced, the key technologies of packaging design such as selection of packaging material and electrical connector, packaging structural design and environmental adaptability design are analyzed and the development prospect of the micro-assembly T/R module packaging for space-borne radar is discussed in this paper. At last the packaging design of a micro-assembly T/R module with high power for space-borne radar is presented as an example. It provides a reference for the subsequent packaging design of micro-assembly T/R module of space-borne radar.