The system states error using classical sliding mode control cannot converge to zero in finite time, so in this paper, a dynamic Terminal sling mode control method based on back stepping design is presented. Terminal sliding mode control strategy is employed to make tracking error converge to zero in finite time. A novel sliding differential dynamic surface is designed to attenuate the chatting. Furthermore, the back stepping design method adapt to complicated systems. The presented algorithm is simple and especially fit for the high-order system. The simplicity, strong robustness, and fast convergence of the proposed control method are verified through the simulation results in the permanent magnet synchronous motor (PMSM). The proposed control method will be of interest to designers of related control systems.