Abstract: A PS-ZVS PWM soft switching power supply is applied in an airborne phased array radar, which realizes both zero-voltage-switching and constant frequency control of power tube and accords with the development trend of electrical and electronic technology. It has high power capacitance and high power density. When compared with traditional lower power capacitance airborne power supply, this power supply gets increased total-power-consumption and more complex heat design. This paper contents the process of heat design for the power supply, especially the design methods for cold plate and high power transformer are discussed in more details.