Abstract: In this paper a new method for the servo-control system design is described. According to the optimal control theory, a new state equation which includes command generator equation is given by introducing a state variable representing the variable frictional disturbance. This new state equation forms the new state feedback in the servo-control system, which not only improves the dynamic response of the system and reduces the sensitivity of the system to parameter changes, but also overcome the low speed jerking motion. Satisfactory results are obtained by calculation and experiment of a practical example.