Aiming at the research on the characteristics of wireless charging coil of electric vehicle the method of coupling resonant circuit combined with Maxwell software modeling is proposed to study its characteristics. Mutual inductance coil of wireless charging system for electric vehicle is an important module to realize wireless charging. The research on its characteristics is helpful to the design and optimization of coil in actual production. Therefore firstly the wireless charging technology for electric vehicles is analyzed and the equivalent model of coupled resonant circuit is established for formula derivation. Then the influence of coil mutual inductance coefficient on system output power and transmission efficiency is studied by MATLAB simulation. Then the simulation model of mutual inductance coil is built in Maxwell software and the number of turns horizontal offset and vertical distance of coil are changed in turn for simulation experiment analysis. The variation of output power and transmission efficiency of the coil under different mutual inductance coefficients the distribution diagram of magnetic induction intensity and the broken line diagram of coupling coefficient are obtained by simulation. According to the simulation results the coil characteristics are analyzed. Finally with the increase of mutual inductance coefficient the output power of the system increases first and then decreases and the transmission efficiency increases continuously. And when the number of turns of the coil decreases the horizontal offset degree of the coil and the vertical distance increase the coupling coefficient of the coil decreases and the reduction amplitude increases.