The speed regulation problem for permanent magnet synchronous motor (PMSM) servo system is studied in this paper. In order to eliminate the chattering phenomenon caused by high switching gain, a composite sliding mode controller is designed for the speed loop. Firstly, a continuous chattering free sliding mode control (CFSMC) method is proposed to ensure the performance of the closed-loop system. Then, an extended state observer (ESO) is used to estimate the disturbances of system and the estimated value is designed as feed-forward compensation, which helps to enhance the disturbance rejection performance. The proposed composite controller combines the merits of both methods. Matlab simulation and TMS320F2808 DSP experiment results indicate the superiority of the proposed method.