In order to analyze conducted EMI noise generated by complex power electronics systems,three theoretical models and its equivalent circuits were proposed by utilizing the electric dipole model,the circuit analysis method and the scattering parameter method,including cross talk mechanism,not-well grounding mechanism and PCB cable impedance mismatch mechanism.Furthermore,the cross talk choke was designed to suppress conducted EMI noise generated by cross talk.The experiment results show a vehicle GPS and RFID card reader system can pass the GB 9254 standard by employing the suggested approaches of this paper and its noise decreased 44.8 and 29.28?dB?V,respectively,so the validity of the approaches was verified.