As a typical closeloop control system, the basic task of the position servo system is to ensure the actuator can accurately track the position commands, and plays an important role in modern production process. Aiming at a servo system with smallpower DC motor, the mathematical modeling was carried out, and subsequently the model was described by means of spacestate expression. Based on the model, a LQR optimal controller was designed. The simulation results show that, the proposed control scheme possesses some performance advantages, including smaller overshoot, shorter regulation time and higher stable accuracy. In addition, the scheme is simple and easy to be realized in engineering.