Abstract: With the development of miniaturization for radar, the design of array power supply with light mass, small size and high stability in harsh environment faces great challenge. In this paper, the new design concept for the array power supply of a vehicle-borne radar is proposed to realize the miniaturization design. Firstly, the detailed structure and thermal design are carried out, the methods of modular design and three-dimensional layout design are used to realize the size and weight requirements. To verify the rationality of the design, simulation results by finite elements analysis software are presented. At last, the design is improved to optimize the performance of the power supply. Results indicate that the array power supply reduces its size by 50% and its weight by 30% while its power density is almost doubled, at the same time, its structure and thermal design satisfy the application requirements. The design errors and development time are effectively reduced by adopting this design concept.