To address the problems that the control performance of conventional sliding mode speed control deteriorates drastically with the changes of the operating parameters of permanent magnet synchronous motor, resulting in large speed jitter, current harmonics and torque pulsations, a novel adaptive fractional-order reaching law sliding mode controller is designed. Firstly, a novel fuzzy adaptive fractional-order reaching law is designed by combining the fractional-order theory and the general power convergence law function, and the level of the adaptive parameters is analysed by orthogonal experiment. Secondly, the parameters are adjusted online using a fuzzy controller to improve the robustness of the controller. Since the introduction of the fuzzy control introduces more current harmonics, the current predictive control with optimal duty cycle is used instead of the traditional current inner loop PI controller. Finally, the simulation model is built and compared with the traditional power reaching law sliding mode controller, and the simulation results show that the three-phase current harmonics of the proposed controller in this paper are reduced by 7.93%, and the speed landing after sudden load addition is reduced by 31.2%, which makes the robustness stronger.