Abstract: The top-down electromagnetic compatibility (EMC) design flow and its applications inmulti-vehicle communication system, which is based on EDA software, are introduced. For the EMC problemssuch as antenna interaction, enclosure leakage and radiation of printed circuit board (PCB) in a four-vehiclecommunication system, the design flow from system level and device level to PCB level is present with simulationprocedure. The results show that this design flow can obviously improve the electromagnetic immunity of thesystem and make the design first pass success.