Due to the rapid development of electric vehicles, the field of wireless charging of electric vehicles is the research direction of this paper. The wireless charging process has nonlinearity, time-varying and uncertainty. The traditional PID controller has been difficult to produce good control effects, so a nonlinear PID controller is introduced. Based on the circuit principle, the state space model is established. Based on the given parameters, the accuracy of the model is verified based on the simulation results. By establishing a good model, the nonlinear PID control of the DC/DC thruster duty cycle is carried out, and the constant power process of the electric vehicle is realized faster by adjusting the nonlinear PID parameters, thereby further improving the actual performance of the electric vehicle.