Aiming at improving the effectiveness for detecting the small pieces of metal foreign object detection (MFOD) scattered in large area of wireless charging system (WCS) of Electric Vehicle (EV), a method for analyzing the electromagnetic characteristics of MFOD coil is presented. The principle of MFOD based on the mistuned appearance of resonant circuits disturbed by metal foreign object (MFO) is introduced. The main factors of affecting the electromagnetic characteristics of MFOD coil are analyzed, and the general design scheme for MFOD coil is proposed as combination of several printed circuit board(PCB) type small coils by series-parallel connection. By the Maxwell simulation, the influences of MFO entering above the MFOD coil on the magnetic field of MFOD coil are analyzed, and the influences of parameters and structural type of MFOD coil on electromagnetic characteristics of MFOD coil are obtained. The simulation result verifies that the presented design scheme for MFOD coil can restrain the induced electric noise under the condition of WCS of EV. The method can be used to guide the design of MFOD coil in WCS of EV.