An adaptive sliding mode controller based on Kalman filter was proposed to reduce load torque ripples and the influence of varying system parameters on the Permanent Magnet Synchronous Motor (PMSM) system. The varying system parameters were evaluated by the adaptive law, and the external disturbance was evaluated by the Kalman filter. The integral action contained in the sliding surface was designed to ensure the steady state error of tracking velocity zero, and the exponential reaching law was employed to increase the reaching speed and to suppress the chattering of sliding mode control. The external disturbance obtained by the Kalman filter was used for feed-forward compensation for the controller output, so the chattering caused by high sliding mode gains was decreased effectively. Experimental results demonstrate that the speed fluctuation is ±1 r/min when the motor reaches the steady state of 600 r/min. Compared with the traditional PI controller, the proposed controller decreases the speed fluctuation by 2% when the torque disturbance of 1.6 N·m is added at the steady speed of 600 r/min. These data verified by simulation and experimental results indicate that the adaptive sliding mode controller based on Kalman filter has anti-disturbance performance and robustness to the AC servo control systems and shows excellent stability.