Aiming at the non-linearity, uncertainty and external interference problems of the magnetic levitation ball system, in order to make the system output have good dynamic quality when tracking the desired position trajectory change, a three-step non-linear controller is designed. The controller is composed of quasi-steady-state control, variable reference feedforward control and error feedback control, and is deduced step by step in a fixed sequence. The derivation process of the three-step nonlinear controller is simple and clear, the structure of the obtained control law is clear, and the multiple differential problems caused by high-order nonlinearity are avoided. The simulation experiment results show that the tracking speed of the three-step nonlinear controller is fast, the overshoot is small, the tracking effect is good, and there is no chattering phenomenon.