In order to reduce the fluctuation of permanent magnet synchronous motor (PMSM) in approach motion status and improve the stability of the control system, a new sliding mode speed control algorithm based on exponential approaching law is designed. Based on the traditional exponential approaching law, a smoother function at the origin is introduced to replace the original symbolic function. The smooth transition of the control algorithm is expected to be realized when the motor runs in the approach motion status. The stability of the algorithm is verified by Lyapunov function. Based on the new control algorithm, a new sliding mode controller is built using MATLAB/Simulink software. The simulation results show that the proposed algorithm can better realize the control of PMSM. Compared with the traditional exponential approaching law control system, the designed system can effectively reduce the system chattering and enhance the robustness.