Nonlinear robust controllers were proposed for permanent magnet linear servo system. In order to reach accurate track of the motor speed and current, an error system dynamic equation based on the motor nonlinear mathematical model was established. The track and disturbance suppression was summed up the design of nonlinear robust controllers. Two theories used in describing nonlinear robust controllers were obtained by defining proper storage function. The equations of nonlinear robust controllers which met disturbance suppression and asymptotical stability were proved. The results of simulation test indicate that the linear servo system with nonlinear robust controllers can guarantee disturbance suppression and the tracks of input signal.