The high-voltage inverter-motor drive system in an electric vehicle is easily to produce strong electric field radiation, which endangers the stable operation of surrounding sensitive electronic equipment. This paper analyzes the common-mode (CM) current paths and its spatial electric field of a vehicle-mounted three-phase inverter-motor system, and proposes a lumped circuit model including CM voltage sources, power cables and pole antenna receiver. The circuit model predicts the electric field emission in the 150 kHz-30 MHz frequency band and is verified by experiment results. In the end, the shielded power cable design is proposed to suppress the electric field radiation.