Based on the technology of magnetic coupling resonance wireless energy transmission, this paper designs a new DD coil structure for electromagnetic coupling resonance wireless charging system. By analyzing the mathematical model of wireless charging coupling mechanism, the relationship between transmission efficiency and frequency, mutual inductance, equivalent load and the resistance of primary and secondary winding is determined. By building the ANSYS simulation model of different magnetic coupling coil structure, the influence of magnetic coupling coil structure change on the coil parameters is compared, and the optimization direction is established. Finally, the system experiment platform is built to verify the optimization scheme of the magnetic coupling mechanism. When the coil offset and input power change, the efficiency of the magnetic coupling mechanism can be kept above 95%. The experimental results are consistent with the simulation results.