The magnetic levitation ball system is a strongly nonlinear system with an open loop instability,and its control input and drive current must vary within a limited range.In order to make the output displacement reach the desired position,anti-windup variable structure PI controller is adopted in this paper to optimize the values of P,I andwith the combination of genetic algorithm,so as to make the ball reach the optimal position output.The experimental results show that,compared with the conventional PI controller,anti-windup variable structure PI control can track the desired position more quickly and stably,and the amplitude of oscillation is significantly reduced.