The bilateral LCC topology provides a highly efficient compensation method for the wireless charging of EV. However, the two compensation coils occupy a large volume. In order to solve the problem of volume increase in electric vehicle charging system and improve the transmission efficiency of system, this paper puts forward a novel method of integrated coil, which integrates the dual polarity compensation coil into single polarity in the main coil. The new electromagnetic coupling mechanism is optimized by using 3D finite element analysis tool ANSYS Maxwell, and the redundant coupling coefficient in the system is eliminated by optimizing the length-width ratios of compensating coil, so as to improve the transmission efficiency of the system. The experimental results show that the wireless charging system using the integrated coil method is less affected by the horizontal or vertical offset of the two coils, and the transmission efficiency of the system is higher.