The electronic throttle of engine is a typical nonlinear object, especially the spring torque and frictional resistance during the rotation process is very complex. Its mathematical model is difficult to be accurately established, and the parameters are not easy to be got. This paper proposes a design method of the internal model controller to solve the nonlinear factor of the electronic throttle. Firstly, the mathematical model of the electronic throttle system is analyzed, and the validity of the model is verified on the Matlab/Simulink simulation platform. Then, the electronic throttle complex field model is established based on the internal model control structure. The nonlinear interference of the system is analyzed, and the internal model controller is designed for the time-varying parameters. The simulation results show that the internal model controller has better performance than the traditional PID and the ordinary sliding mode control in the case of relatively accurate model, and the robustness of the internal model controller guarantees that its performance is still better than the traditional PID in the case of mismatched model. In the design method of the internal model controller proposed in this paper, system parameters are not required to design the feedforward filter, but the ideal steady-state response and disturbance response is still guaranteed. Therefore, this method has better practical significance compared with many model-specific control strategies.