While applying Sliding Mode Control (SMC) algorithm, the time and space delay and dead zone may cause the unexpected output vibration in actual controller design. In this paper, the damage to actual system and the causes of its existence are analyzed. Considering the inherent random disturbance and noise in servo system, a SMC algorithm with exponent approach law based on Kalman filtering is proposed. The simulation shows that compared with common sliding mode algorithm, the new algorithm can not only suppress the vibration but improve the dynamic quality of servo system.