In order to solve the problems that the d-q axis current fluctuates greatly when the traditional sliding mode reach law control is applied to the vector control system of permanent magnet synchronous motor, a new sliding mode control strategy based on the reaching law is proposed. Firstly, a new sliding mode reaching law (NSMRL) algorithm is designed by combining the general power reaching law and the power function of speed error, and its stability is proved by Lyapunov function. Secondly, in order to further reduce the current harmonic proportion of permanent magnet synchronous motor and improve the current pulsation problem, this paper proposes to combine the extended Kalman filter (EKF) with a new reaching law to obtain the optimal current prediction in the sense of minimum variance. The simulation results show that compared with the traditional sliding mode control reaching law, the controller using NSMRL can reduce overshoot by 21.73% during startup and speed drop by 31 r/min after sudden loading. After the introduction of EKF, the d-q axis current fluctuation is reduced by 92% compared with NSMRL.