Abstract: In radio frequency system, the interference exists in many different ways, once the design of the supply power is not considered comprehensive, it will cause much unwanted interference and noise, which can decrease the expected design target and discount the performance of communications system. How to suppress and weaken the interference and noise? It is a key to reach the communication system KPI of equipment. This article discusses these problems from the follow- ing aspects: selection of power supply components, setting of power supply layers and ground layers, layout of power supply components, shielding and isolation of different power supply, filtering and decoupling of power supply, even power supply routing, and so on . Those means can improve EMC effectively. This design of power supply of this article also refers to the corresponding solutions, and applied them to the practical design.