Abstract: The optimum design process of a radar antenna structure is introduced in this paper. According to the characteristics of the installation space of the radar antenna and the related technical requirements, two aspects are elaborated in detail. For one thing, the internal equipment of the antenna is divided into the transmitter extension, power supply monitoring extension, power divider components and antenna sub-unit by modular design method. Structure design and thermal design for each module are carried out and thus the problems of insufficient installation space and complex cable wiring in the antenna are solved. For another, the antenna framework is redesigned with the shape stealth technology, which reduces the radar cross section and improves the stealth performance of the antenna . Finally ,the stealth performance , thermal design and mechanical properties are analyzed by software simulation technology. The simulation results meet the design requirements.